feat: design system overhaul — sidebar, AI chats, settings, brainstorm, color cleanup

- Sidebar: dynamic brand-accent colors, brainstorm section restyled
- AI chat general: popup panel with expand/collapse, hides when contextual AI open
- AI chat contextual: tabs reordered (Actions first), X close button, height fix
- Settings: all tabs restyled, 6 new color presets (sage, terracotta, iron, etc.)
- Global color cleanup: emerald/orange hardcoded → brand-accent dynamic
- Brainstorm page: orange → brand-accent throughout
- PageEntry animation component added to key pages
- Floating AI button: bg-brand-accent instead of hardcoded black
- i18n: all 15 locales updated with new AI/billing keys
- Billing: freemium quota tracking, BYOK, stripe subscription scaffolding
- Admin: integrated into new design
- AGENTS.md + CLAUDE.md project rules added

.cursor/hooks/state/continual-learning.json

@@ -1,8 +1,8 @@
 {
   "version": 1,
-  "lastRunAtMs": 0,
-  "turnsSinceLastRun": 8,
-  "lastTranscriptMtimeMs": null,
-  "lastProcessedGenerationId": "d40421fd-8dd1-472a-9807-a1c4f939b552",
+  "lastRunAtMs": 1778916916450,
+  "turnsSinceLastRun": 6,
+  "lastTranscriptMtimeMs": 1778916916347.422,
+  "lastProcessedGenerationId": "6a9dfdc8-438b-497e-831b-ad0079ebea2a",
   "trialStartedAtMs": null
 }