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/screens/notes/note_edit_screen.dart

@@ -1,9 +1,11 @@
 import 'package:flutter/material.dart';
+import 'package:lucide_icons/lucide_icons.dart';
 import 'package:flutter_markdown_plus/flutter_markdown_plus.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../core/exceptions.dart';
+import '../../core/theme.dart';
 import '../../core/wikilink_syntax.dart';
 import '../../providers/api_client_provider.dart';
 import '../../providers/notes_provider.dart';
@@ -85,6 +87,9 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
           ),
           TextButton(
             onPressed: () => Navigator.pop(dialogContext, true),
+            style: TextButton.styleFrom(
+              foregroundColor: Theme.of(dialogContext).extension<ActionColors>()!.destructive,
+            ),
             child: const Text('Delete'),
           ),
         ],
@@ -163,12 +168,12 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
             actions: [
               if (widget.noteId != null)
                 IconButton(
-                  icon: const Icon(Icons.delete_outline),
+                  icon: const Icon(LucideIcons.trash2),
                   tooltip: 'Delete',
                   onPressed: _delete,
                 ),
               IconButton(
-                icon: Icon(_preview ? Icons.edit : Icons.preview),
+                icon: Icon(_preview ? LucideIcons.pencil : LucideIcons.eye),
                 tooltip: _preview ? 'Edit' : 'Preview',
                 onPressed: () => setState(() => _preview = !_preview),
               ),
@@ -179,7 +184,7 @@ class _NoteEditScreenState extends ConsumerState<NoteEditScreen> {
                         height: 20,
                         child: CircularProgressIndicator(strokeWidth: 2),
                       )
-                    : const Icon(Icons.check),
+                    : const Icon(LucideIcons.check),
                 onPressed: _saving ? null : _save,
               ),
             ],
@@ -272,7 +277,7 @@ class _TagInput extends StatelessWidget {
             label: Text('#$tag', style: const TextStyle(fontSize: 12)),
             materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
             padding: const EdgeInsets.symmetric(horizontal: 4),
-            deleteIcon: const Icon(Icons.close, size: 14),
+            deleteIcon: const Icon(LucideIcons.x, size: 14),
             onDeleted: () => onRemove(tag),
           ),
         ),