feat(studio): de-jargonize, reveal-in-OS, copyable errors, today carousel, AppBar alignment, F∆I window title (v0.34.0)

Sweeping pass against six user reports collected this session.

1. "Capabilities ist nicht deutsch, Chain auch nicht."
   The DE locale still leaked English vocabulary. Replaced
   "Capabilities" → "Fähigkeiten" and "Chain" / "Hash-Chain"
   → "Kette" / "Hash-Kette" everywhere — store search hint,
   recommended-source body, federated toast, doctor summary
   chain row, modules panel summary, MCP / n8n hints, the
   approvals history blurb. Wire-level identifiers
   (`chain.reset`) stay as code.

2. "Bei Fehlern unten muss man die auch ins clipboard
   kopieren können." New `FaiErrorBox` widget: selectable
   monospace block with a small copy-to-clipboard icon
   button that flips to a checkmark for two seconds after
   click. Applied to the Doctor update banner output and
   the Settings channel toast — the two places long
   stderr / stdout lands.

3. "Öffnen bei Log kann es nicht öffnen. Audit-DB auch
   nicht. PID auch nicht."
   Cause: `SystemActions.openInOs` shells out to `open` /
   `xdg-open` on file paths the OS has no default handler
   for (SQLite DB, PID file, log without an .ext that
   binds). New `revealInOs` uses `open -R` on macOS,
   `explorer /select,` on Windows, and the parent
   directory via `xdg-open` on Linux. Doctor's path rows
   carry an `isDirectory` flag that routes through the new
   `openOrReveal` so files reveal in Finder / Explorer
   instead of failing silently.

4. "Oben im Store könnte man diesen Redaktionshinweis auch
   so bauen, dass man mit pfeil nach rechts links auch
   weitere anzeigen kann."
   The Today-Hero became a carousel. Curated fallback
   list grew from one entry to four (public sources, the
   sandbox-by-default permission story, the hash-chained
   audit story, the air-gap-ready single-binary pitch).
   Hero gets prev / next chevrons plus a dot indicator
   when the current snapshot has more than one slide.
   Operator-accepted stories stay single — the carousel
   collapses when there's only one to show.

5. "Ich fände es schöner wenn rechts und links im Store
   die Abstände konsistent sind, das Reload-Symbol rechts
   ist zu weit rechts und Store links auch nicht bündig."
   AppBar now has `titleSpacing: FaiSpace.xl` so the
   title's left edge sits flush with the body's left
   padding (24 dp), and the trailing `SizedBox` after the
   reload icon shrunk so the icon's outer edge meets the
   right edge of the rightmost grid card.

6. "Oben der Titel zeigt fai_studio an, das sollte F∆I
   Studio sein." The OS window title was the
   pubspec-derived "fai_studio". Macos/Linux/Windows
   runners now hard-code "F∆I Studio" (with the U+2206
   triangle escape so the C++ source stays ASCII). macOS
   bundle name and display name lifted out of the
   PRODUCT_NAME variable for the same reason.

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

lib/l10n/app_localizations_en.dart

@@ -80,6 +80,12 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get buttonReadDocs => 'Read docs';
 
+  @override
+  String get buttonCopy => 'Copy to clipboard';
+
+  @override
+  String get buttonCopied => 'Copied';
+
   @override
   String get settingsTitle => 'Hub endpoint';