feat: editor improvements and architectural grid prototype

Multiple feature additions and improvements across the application:

- NextGen Editor: drag handles, smart paste, block actions
- Structured views: Kanban and table layouts for notes
- Architectural Grid: new brainstorming/agent interface prototype
- Flashcards: SM-2 revision algorithm with AI generation
- MCP server: robustness improvements
- Graph/PDF chat: fix click propagation and copy behavior
- Various UI/UX enhancements and bug fixes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -1,8 +1,8 @@
 {
   "version": 1,
-  "lastRunAtMs": 1779646930753,
-  "turnsSinceLastRun": 6,
-  "lastTranscriptMtimeMs": 1779646930615.2869,
-  "lastProcessedGenerationId": "c2a9fd9d-5b50-42a8-8b17-e414b0be891e",
+  "lastRunAtMs": 1779909959153,
+  "turnsSinceLastRun": 4,
+  "lastTranscriptMtimeMs": 1779909958790.594,
+  "lastProcessedGenerationId": "5bd39ea3-9f17-44d1-8aed-3cc8f3673e97",
   "trialStartedAtMs": null
 }