refactor: rename internal Fai* design system + fai_ helpers to chain

The Studio design system, widgets and helpers carried a Fai* / fai_
prefix (FaiSpace, FaiColors, FaiTheme, FaiLog, 17 fai_*.dart files, the
faiBinary* l10n keys). Studio is the Ch∆In product, so rename them to
Chain* / chain_ — carefully preserving English fail/failure/failed.
Also fix stale references: the 'fai' binary in l10n strings -> 'chain',
FAI_* env vars (FAI_BIN/DATA_DIR/MODULES_DIR/TODAY/BOOTSTRAP_TOKEN) ->
CHAIN_*, fai_platform -> fai_chain, fai_hub -> chain_hub. Vendor
security-hook tooling (FAI_BANNED_TERMS_FILE) + the .fai bundle ext left.
flutter analyze + test: clean (20 passed).

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/theme/theme.dart

@@ -5,8 +5,8 @@ import 'package:flutter_markdown_plus/flutter_markdown_plus.dart';
 
 import 'tokens.dart';
 
-class FaiTheme {
-  FaiTheme._();
+class ChainTheme {
+  ChainTheme._();
 
   /// Bundled font families. Declared in pubspec.yaml `fonts:` and
   /// shipped as TTF assets under `assets/fonts/` — NOT fetched at
@@ -79,7 +79,7 @@ class FaiTheme {
   }
 
   /// JetBrains Mono for monospaced technical content. Used by
-  /// FaiMono helper. Only Regular (400) and Medium (500) weights
+  /// ChainMono helper. Only Regular (400) and Medium (500) weights
   /// are bundled — heavier requests fall back to the nearest.
   static TextStyle mono({
     double size = 12,
@@ -125,25 +125,25 @@ class FaiTheme {
       ).copyWith(backgroundColor: Colors.transparent),
       codeblockDecoration: BoxDecoration(
         color: theme.colorScheme.surfaceContainerHigh,
-        borderRadius: BorderRadius.circular(FaiRadius.sm),
+        borderRadius: BorderRadius.circular(ChainRadius.sm),
         border: Border.all(color: theme.colorScheme.outlineVariant),
       ),
-      codeblockPadding: const EdgeInsets.all(FaiSpace.md),
+      codeblockPadding: const EdgeInsets.all(ChainSpace.md),
       blockquote: theme.textTheme.bodyMedium?.copyWith(
         color: theme.colorScheme.onSurface,
       ),
       blockquoteDecoration: BoxDecoration(
         color: theme.colorScheme.surfaceContainer,
-        borderRadius: BorderRadius.circular(FaiRadius.sm),
+        borderRadius: BorderRadius.circular(ChainRadius.sm),
         border: Border(
           left: BorderSide(color: theme.colorScheme.primary, width: 3),
         ),
       ),
       blockquotePadding: const EdgeInsets.fromLTRB(
-        FaiSpace.md,
-        FaiSpace.sm,
-        FaiSpace.sm,
-        FaiSpace.sm,
+        ChainSpace.md,
+        ChainSpace.sm,
+        ChainSpace.sm,
+        ChainSpace.sm,
       ),
       tableCellsDecoration: BoxDecoration(
         color: theme.colorScheme.surfaceContainerHigh,
@@ -164,32 +164,32 @@ class FaiTheme {
   static ThemeData dark() {
     final scheme = ColorScheme(
       brightness: Brightness.dark,
-      primary: FaiColors.accent,
-      onPrimary: FaiColors.black,
-      primaryContainer: FaiColors.accentMuted,
-      onPrimaryContainer: FaiColors.textStrong,
-      secondary: FaiColors.accentDeep,
-      onSecondary: FaiColors.black,
-      secondaryContainer: FaiColors.surfaceHigh,
-      onSecondaryContainer: FaiColors.text,
-      tertiary: FaiColors.accent,
-      onTertiary: FaiColors.black,
-      tertiaryContainer: FaiColors.surfaceHigh,
-      onTertiaryContainer: FaiColors.text,
-      error: FaiColors.danger,
-      onError: FaiColors.textStrong,
+      primary: ChainColors.accent,
+      onPrimary: ChainColors.black,
+      primaryContainer: ChainColors.accentMuted,
+      onPrimaryContainer: ChainColors.textStrong,
+      secondary: ChainColors.accentDeep,
+      onSecondary: ChainColors.black,
+      secondaryContainer: ChainColors.surfaceHigh,
+      onSecondaryContainer: ChainColors.text,
+      tertiary: ChainColors.accent,
+      onTertiary: ChainColors.black,
+      tertiaryContainer: ChainColors.surfaceHigh,
+      onTertiaryContainer: ChainColors.text,
+      error: ChainColors.danger,
+      onError: ChainColors.textStrong,
       errorContainer: const Color(0xFF3F1518),
       onErrorContainer: const Color(0xFFFCA5A5),
-      surface: FaiColors.black,
-      onSurface: FaiColors.text,
-      onSurfaceVariant: FaiColors.muted,
-      outline: FaiColors.border,
-      outlineVariant: FaiColors.border,
-      surfaceContainerLowest: FaiColors.black,
-      surfaceContainerLow: FaiColors.surface,
-      surfaceContainer: FaiColors.surface,
-      surfaceContainerHigh: FaiColors.surfaceHigh,
-      surfaceContainerHighest: FaiColors.surfaceHigh,
+      surface: ChainColors.black,
+      onSurface: ChainColors.text,
+      onSurfaceVariant: ChainColors.muted,
+      outline: ChainColors.border,
+      outlineVariant: ChainColors.border,
+      surfaceContainerLowest: ChainColors.black,
+      surfaceContainerLow: ChainColors.surface,
+      surfaceContainer: ChainColors.surface,
+      surfaceContainerHigh: ChainColors.surfaceHigh,
+      surfaceContainerHighest: ChainColors.surfaceHigh,
     );
     return _build(scheme);
   }
@@ -197,32 +197,32 @@ class FaiTheme {
   static ThemeData light() {
     final scheme = ColorScheme(
       brightness: Brightness.light,
-      primary: FaiColors.accentDeep,
-      onPrimary: FaiColors.lightSurface,
+      primary: ChainColors.accentDeep,
+      onPrimary: ChainColors.lightSurface,
       primaryContainer: const Color(0xFFE0F2FE),
-      onPrimaryContainer: FaiColors.accentMuted,
-      secondary: FaiColors.accentMuted,
-      onSecondary: FaiColors.lightSurface,
-      secondaryContainer: FaiColors.lightSurfaceHigh,
-      onSecondaryContainer: FaiColors.lightText,
-      tertiary: FaiColors.accentDeep,
-      onTertiary: FaiColors.lightSurface,
+      onPrimaryContainer: ChainColors.accentMuted,
+      secondary: ChainColors.accentMuted,
+      onSecondary: ChainColors.lightSurface,
+      secondaryContainer: ChainColors.lightSurfaceHigh,
+      onSecondaryContainer: ChainColors.lightText,
+      tertiary: ChainColors.accentDeep,
+      onTertiary: ChainColors.lightSurface,
       tertiaryContainer: const Color(0xFFE0F2FE),
-      onTertiaryContainer: FaiColors.accentMuted,
-      error: FaiColors.danger,
-      onError: FaiColors.lightSurface,
+      onTertiaryContainer: ChainColors.accentMuted,
+      error: ChainColors.danger,
+      onError: ChainColors.lightSurface,
       errorContainer: const Color(0xFFFEE2E2),
       onErrorContainer: const Color(0xFF7F1D1D),
-      surface: FaiColors.lightCanvas,
-      onSurface: FaiColors.lightText,
-      onSurfaceVariant: FaiColors.lightMuted,
-      outline: FaiColors.lightBorder,
-      outlineVariant: FaiColors.lightBorder,
-      surfaceContainerLowest: FaiColors.lightCanvas,
-      surfaceContainerLow: FaiColors.lightSurface,
-      surfaceContainer: FaiColors.lightSurface,
-      surfaceContainerHigh: FaiColors.lightSurfaceHigh,
-      surfaceContainerHighest: FaiColors.lightSurfaceHigh,
+      surface: ChainColors.lightCanvas,
+      onSurface: ChainColors.lightText,
+      onSurfaceVariant: ChainColors.lightMuted,
+      outline: ChainColors.lightBorder,
+      outlineVariant: ChainColors.lightBorder,
+      surfaceContainerLowest: ChainColors.lightCanvas,
+      surfaceContainerLow: ChainColors.lightSurface,
+      surfaceContainer: ChainColors.lightSurface,
+      surfaceContainerHigh: ChainColors.lightSurfaceHigh,
+      surfaceContainerHighest: ChainColors.lightSurfaceHigh,
     );
     return _build(scheme);
   }
@@ -256,7 +256,7 @@ class FaiTheme {
         color: scheme.surfaceContainer,
         elevation: 0,
         shape: RoundedRectangleBorder(
-          borderRadius: BorderRadius.circular(FaiRadius.md),
+          borderRadius: BorderRadius.circular(ChainRadius.md),
           side: BorderSide(color: scheme.outlineVariant),
         ),
         margin: EdgeInsets.zero,
@@ -266,14 +266,14 @@ class FaiTheme {
           backgroundColor: scheme.primary,
           foregroundColor: scheme.onPrimary,
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(FaiRadius.sm),
+            borderRadius: BorderRadius.circular(ChainRadius.sm),
           ),
           padding: const EdgeInsets.symmetric(
-            horizontal: FaiSpace.lg,
-            vertical: FaiSpace.md,
+            horizontal: ChainSpace.lg,
+            vertical: ChainSpace.md,
           ),
           textStyle: textTheme.labelMedium,
-          animationDuration: FaiMotion.fast,
+          animationDuration: ChainMotion.fast,
         ),
       ),
       outlinedButtonTheme: OutlinedButtonThemeData(
@@ -281,14 +281,14 @@ class FaiTheme {
           foregroundColor: scheme.onSurface,
           side: BorderSide(color: scheme.outline),
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(FaiRadius.sm),
+            borderRadius: BorderRadius.circular(ChainRadius.sm),
           ),
           padding: const EdgeInsets.symmetric(
-            horizontal: FaiSpace.lg,
-            vertical: FaiSpace.md,
+            horizontal: ChainSpace.lg,
+            vertical: ChainSpace.md,
           ),
           textStyle: textTheme.labelMedium,
-          animationDuration: FaiMotion.fast,
+          animationDuration: ChainMotion.fast,
         ),
       ),
       iconButtonTheme: IconButtonThemeData(
@@ -323,7 +323,7 @@ class FaiTheme {
         ),
         behavior: SnackBarBehavior.floating,
         shape: RoundedRectangleBorder(
-          borderRadius: BorderRadius.circular(FaiRadius.sm),
+          borderRadius: BorderRadius.circular(ChainRadius.sm),
         ),
       ),
     );