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_detail_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/constants.dart';
+import '../../core/theme.dart';
 import '../../core/wikilink_syntax.dart';
 import '../../providers/notes_provider.dart';
 
@@ -44,13 +46,13 @@ class NoteDetailScreen extends ConsumerWidget {
             data: (note) => Row(
               children: [
                 IconButton(
-                  icon: const Icon(Icons.edit),
+                  icon: const Icon(LucideIcons.pencil),
                   onPressed: () => context.push(
                     Routes.noteEdit.replaceFirst(':id', '$noteId'),
                   ),
                 ),
                 IconButton(
-                  icon: const Icon(Icons.delete),
+                  icon: const Icon(LucideIcons.trash2),
                   onPressed: () async {
                     final confirm = await showDialog<bool>(
                       context: context,
@@ -65,6 +67,11 @@ class NoteDetailScreen extends ConsumerWidget {
                           TextButton(
                             onPressed: () =>
                                 Navigator.pop(dialogContext, true),
+                            style: TextButton.styleFrom(
+                              foregroundColor: Theme.of(dialogContext)
+                                  .extension<ActionColors>()!
+                                  .destructive,
+                            ),
                             child: const Text('Delete'),
                           ),
                         ],