feat(theme): shift Android palette from indigo to deep violet to match web identity

lib/core/theme.dart

@@ -3,21 +3,21 @@ import 'package:google_fonts/google_fonts.dart';
 
 // ── Colour constants ──────────────────────────────────────────────────────────
 
-const _darkBackground    = Color(0xFF111113);
+const _darkBackground    = Color(0xFF0F0F14);
-const _darkSurface       = Color(0xFF18181C);
+const _darkSurface       = Color(0xFF16161F);
-const _darkSurfaceVar    = Color(0xFF1E1E24);
+const _darkSurfaceVar    = Color(0xFF1A1A24);
-const _darkPrimary       = Color(0xFF6366F1);
+const _darkPrimary       = Color(0xFF7C3AED);
-const _darkOnSurface     = Color(0xFFE8E8F0);
+const _darkOnSurface     = Color(0xFFE4E4F0);
 const _darkOnSurfaceVar  = Color(0xFF8888A8);
-const _darkOutline       = Color(0xFF2E2E3A);
+const _darkOutline       = Color(0xFF2A2A3A);
 
-const _lightBackground   = Color(0xFFF4F4F8);
+const _lightBackground   = Color(0xFFF5F5FB);
 const _lightSurface      = Color(0xFFFFFFFF);
-const _lightSurfaceVar   = Color(0xFFF0F0F5);
+const _lightSurfaceVar   = Color(0xFFF0F0F8);
-const _lightPrimary      = Color(0xFF4F46E5);
+const _lightPrimary      = Color(0xFF7C3AED);
-const _lightOnSurface    = Color(0xFF18181C);
+const _lightOnSurface    = Color(0xFF1A1A1A);
-const _lightOnSurfaceVar = Color(0xFF6B6B88);
+const _lightOnSurfaceVar = Color(0xFF666666);
-const _lightOutline      = Color(0xFFD4D4E4);
+const _lightOutline      = Color(0xFFDDDDE8);
 
 // ── Typography ─────────────────────────────────────────────────────────────────
 
@@ -41,7 +41,7 @@ ThemeData fabledDarkTheme() {
     brightness:          Brightness.dark,
     primary:             _darkPrimary,
     onPrimary:           Colors.white,
-    primaryContainer:    const Color(0xFF3730A3),
+    primaryContainer:    const Color(0xFF5B21B6),
     onPrimaryContainer:  _darkOnSurface,
     secondary:           _darkPrimary,
     onSecondary:         Colors.white,
@@ -118,7 +118,7 @@ ThemeData fabledLightTheme() {
     brightness:          Brightness.light,
     primary:             _lightPrimary,
     onPrimary:           Colors.white,
-    primaryContainer:    const Color(0xFFE0E0FF),
+    primaryContainer:    const Color(0xFFEDE5FF),
     onPrimaryContainer:  _lightOnSurface,
     secondary:           _lightPrimary,
     onSecondary:         Colors.white,
@@ -218,15 +218,15 @@ class GradientButton extends StatelessWidget {
               : const LinearGradient(
                   begin: Alignment.topLeft,
                   end: Alignment.bottomRight,
-                  colors: [Color(0xFF6366F1), Color(0xFF4F46E5)],
+                  colors: [Color(0xFF7C3AED), Color(0xFF5B21B6)],
                 ),
-          color: disabled ? const Color(0xFF6366F1) : null,
+          color: disabled ? const Color(0xFF7C3AED) : null,
           borderRadius: BorderRadius.circular(12),
           boxShadow: disabled
               ? null
               : [
                   BoxShadow(
-                    color: const Color(0xFF6366F1).withValues(alpha: 0.35),
+                    color: const Color(0xFF7C3AED).withValues(alpha: 0.45),
                     blurRadius: 8,
                     offset: const Offset(0, 3),
                   ),

lib/screens/briefing/briefing_screen.dart

@@ -462,7 +462,7 @@ class _GradientSendButton extends StatelessWidget {
             : const LinearGradient(
                 begin: Alignment.topLeft,
                 end: Alignment.bottomRight,
-                colors: [Color(0xFF6366F1), Color(0xFF4F46E5)],
+                colors: [Color(0xFF7C3AED), Color(0xFF5B21B6)],
               ),
         color: disabled ? scheme.onSurface.withValues(alpha: 0.12) : null,
         borderRadius: BorderRadius.circular(10),

lib/screens/calendar/event_form_sheet.dart

@@ -57,7 +57,7 @@ class _EventFormSheetState extends ConsumerState<EventFormSheet> {
     '#EF4444',
     '#F59E0B',
     '#10B981',
-    '#6366F1',
+    '#7C3AED',
     '#8B5CF6',
     '#EC4899',
   ];

lib/screens/library/project_tasks_screen.dart

@@ -55,11 +55,11 @@ class _ProjectTasksScreenState extends ConsumerState<ProjectTasksScreen> {
   }
 
   Color _parseColor(String? hex) {
-    if (hex == null || hex.isEmpty) return const Color(0xFF6366F1);
+    if (hex == null || hex.isEmpty) return const Color(0xFF7C3AED);
     try {
       return Color(int.parse(hex.replaceFirst('#', '0xFF')));
     } catch (_) {
-      return const Color(0xFF6366F1);
+      return const Color(0xFF7C3AED);
     }
   }