feat(design): surface phase — Lucide icons, input radius, Illuminated Transcript, ActionColors

Per-screen application of the design system to the Flutter app.
Mirrors the web's surface phase landed in FabledScribe v26.04.28.1.
Foundation port shipped in 0f05f47; this is the surface work.

Lucide icon migration
- Added lucide_icons ^0.257.0 dependency
- 107 Material Icons references → LucideIcons across 21 files. Drop-in
  IconData swap (Icon(LucideIcons.X) instead of Icon(Icons.x)).
- Lucide import added to each touched file.

Input border radius
- theme.dart inputDecorationTheme borderRadius 24 → 8 in both light
  and dark themes. Doc says radius-md (8px) for inputs; previous pill
  shape was Material default that the doc deviates from.

Illuminated Transcript pattern (ChatMessageBubble)
- User bubble: accent-tinted border → neutral Pewter (scheme.outline).
  Asymmetric corner already correct (bottomRight 4px).
- Assistant bubble: topLeft corner 4 → 16; only bottomLeft stays 4
  (the "tail" effect, mirroring web's `border-bottom-left-radius: 4px`).
  Background switched from surfaceContainerHighest (Slate) to surface
  (Iron) per the doc spec "card surface".
- Assistant bubble glow shadow added — accent-tinted blur (28px alpha
  0.14) + depth shadow (8px alpha 0.4 black). Mirrors web's
  --color-bubble-asst-shadow.

ActionColors wiring (Hybrid rule)
- 5 'Delete' confirm buttons across notes / tasks / chat conversations
  / calendar event sheet → Oxblood action-destructive via the
  ActionColors ThemeExtension defined in the foundation port. Foreground
  for ghost/text variants, backgroundColor for filled.
- Calendar event Save button → Moss action-primary. The first call
  site to wire ActionColors.primary; serves as the pattern for future
  Save reclassifications.
- Other Save buttons (note edit, task edit, project edit, etc.) still
  flow through colorScheme.primary (dusty violet) and read as
  brand-moment. Reclassifying those is deferred — the wiring pattern
  is established and can be applied incrementally as files are touched.

Indigo cleanup
- 4 hardcoded #7C3AED / #5B21B6 literals → dusty-violet equivalents
  (#5B4A8A / #3F3560). Spots: project_tasks_screen color fallback
  (×2), journal_screen gradient.

Verification
- flutter analyze: No issues found

What's deferred
- Per-screen Save / Cancel reclassification beyond the calendar event
  Save button. Wiring pattern established; rollout opportunistic.
- Long-form 1.7 line-height on assistant Markdown content (would
  require MarkdownStyleSheet work; minor).
- Surface walk on Knowledge / Projects / Settings screens for any
  hardcoded styling that needs touch.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/widgets/tool_call_chip.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:lucide_icons/lucide_icons.dart';
 import 'package:go_router/go_router.dart';
 
 import '../core/constants.dart';
@@ -45,24 +46,24 @@ const Map<String, String> _toolLabels = {
 };
 
 IconData _iconFor(String fn) {
-  if (fn.contains('note')) return Icons.sticky_note_2_outlined;
-  if (fn.contains('task')) return Icons.check_circle_outline;
+  if (fn.contains('note')) return LucideIcons.stickyNote;
+  if (fn.contains('task')) return LucideIcons.checkCircle2;
   if (fn.contains('event') || fn.contains('calendar')) {
-    return Icons.event_outlined;
+    return LucideIcons.calendarCheck;
   }
-  if (fn.contains('project')) return Icons.folder_outlined;
-  if (fn.contains('milestone')) return Icons.flag_outlined;
+  if (fn.contains('project')) return LucideIcons.folder;
+  if (fn.contains('milestone')) return LucideIcons.flag;
   if (fn.contains('web') || fn.contains('research') || fn.contains('article')) {
-    return Icons.public;
+    return LucideIcons.globe;
   }
-  if (fn.contains('image')) return Icons.image_outlined;
+  if (fn.contains('image')) return LucideIcons.image;
   if (fn.contains('person') || fn.contains('profile')) {
-    return Icons.person_outline;
+    return LucideIcons.user;
   }
-  if (fn.contains('place')) return Icons.place_outlined;
-  if (fn.contains('rag') || fn.contains('scope')) return Icons.tune;
-  if (fn.contains('calculate')) return Icons.calculate_outlined;
-  return Icons.auto_awesome;
+  if (fn.contains('place')) return LucideIcons.mapPin;
+  if (fn.contains('rag') || fn.contains('scope')) return LucideIcons.sliders;
+  if (fn.contains('calculate')) return LucideIcons.calculator;
+  return LucideIcons.sparkles;
 }
 
 /// Pull the destination route for this tool call from its `result` payload,
@@ -161,7 +162,7 @@ class ToolCallChip extends StatelessWidget {
           ),
           if (route != null) ...[
             const SizedBox(width: 4),
-            Icon(Icons.arrow_forward, size: 11, color: fg),
+            Icon(LucideIcons.arrowRight, size: 11, color: fg),
           ],
         ],
       ),