feat(editor): five distinct type colours + wired/total badge in step header

Two operator-visible improvements:

 - Five payload types now get five distinct hues that
   survive both light and dark themes:
     text   → blue (0xFF42A5F5)
     bytes  → deep orange (0xFFFF7043)
     json   → purple (0xFFAB47BC)
     file   → green (0xFF66BB6A)
     number → amber (0xFFFFCA28)
   Previously bytes + file shared a colour and the palette
   collapsed under custom theme plugins. Hardcoded hues
   keep them readable everywhere.

 - Step headers now carry a small "wired/total" badge.
   When all with-fields carry a `$src.field` reference,
   the badge collapses to a green check icon — the visual
   "this module is fully wired" signal Stefan asked for.
   Partial-wiring shows e.g. "3/5" in a pill matching the
   step accent. Endpoint nodes don't render the badge
   (ratio doesn't apply there).

Computed live from graph.edges + step.with_ values, so the
indicator updates the moment an operator drags a
connection in or out.

Version 0.5.0 -> 0.5.1.

Signed-off-by: flemming-it <sf@flemming.it>

lib/src/widgets/flow_node.dart

@@ -117,6 +117,14 @@ class FlowNode extends StatelessWidget {
   /// "must wire" and this is empty.
   final Set<String> optionalLabels;
 
+  /// How many of [inputPortLabels] are currently wired to an
+  /// upstream source. When equal to the total count, the
+  /// header paints a "complete" check mark; otherwise it
+  /// renders the ratio (e.g. "3/5") so the operator sees
+  /// at a glance what's still to wire. Set to null on
+  /// endpoint nodes where the ratio doesn't apply.
+  final int? wiredCount;
+
   /// Right-click handler on the node body. Canvas wires this
   /// to a popup menu at the cursor position (Duplicate /
   /// Delete / Disconnect inputs etc.).
@@ -136,6 +144,7 @@ class FlowNode extends StatelessWidget {
     this.kind = NodeVisualKind.module,
     this.portSide = NodePortSide.left,
     this.optionalLabels = const {},
+    this.wiredCount,
     this.selected = false,
     this.status = FlowNodeStatus.idle,
     this.onTap,
@@ -224,7 +233,12 @@ class FlowNode extends StatelessWidget {
                     ),
                   ),
                 ),
-                if (status != FlowNodeStatus.idle) _statusDot(theme),
+                if (wiredCount != null && inputPortLabels.isNotEmpty)
+                  _wiredBadge(theme, accent),
+                if (status != FlowNodeStatus.idle) ...[
+                  const SizedBox(width: 4),
+                  _statusDot(theme),
+                ],
               ],
             ),
           ),
@@ -313,6 +327,38 @@ class FlowNode extends StatelessWidget {
     );
   }
 
+  Widget _wiredBadge(ThemeData theme, Color accent) {
+    final total = inputPortLabels.length;
+    final wired = wiredCount ?? 0;
+    final complete = wired >= total && total > 0;
+    if (complete) {
+      return Padding(
+        padding: const EdgeInsets.only(left: 4),
+        child: Icon(Icons.check_circle, size: 14, color: Colors.green.shade400),
+      );
+    }
+    return Padding(
+      padding: const EdgeInsets.only(left: 4),
+      child: Container(
+        padding: const EdgeInsets.symmetric(horizontal: 5, vertical: 1),
+        decoration: BoxDecoration(
+          color: accent.withValues(alpha: 0.12),
+          borderRadius: BorderRadius.circular(8),
+          border: Border.all(color: accent.withValues(alpha: 0.4)),
+        ),
+        child: Text(
+          '$wired/$total',
+          style: theme.textTheme.labelSmall?.copyWith(
+            fontFamily: 'monospace',
+            fontSize: 9,
+            fontWeight: FontWeight.w600,
+            color: accent,
+          ),
+        ),
+      ),
+    );
+  }
+
   Widget _statusDot(ThemeData theme) {
     final color = switch (status) {
       FlowNodeStatus.running => theme.colorScheme.primary,