Release v5.2.1: Fix project filter synchronization bugs

This patch release fixes critical race conditions and state synchronization
issues in the viewer UI's project filtering system.

**Bug Fixes:**
- Fixed race condition where offset wasn't reset when filter changed
- Fixed state ref synchronization causing stale hasMore values
- Fixed batched state updates mixing data from different projects
- Fixed useEffect dependency cycle causing double renders
- Combined useEffect hooks for guaranteed execution order

**Technical Changes:**
- Updated App.tsx: Fixed filter change detection and data reset logic
- Updated usePagination.ts: Improved offset and state ref handling
- Updated data.ts: Simplified mergeAndDeduplicateByProject validation
- Updated SessionStore.ts: Filter NULL/empty projects from dropdown
- Added investigated field to Summary interface

**Files Updated:**
- package.json: version 5.2.0 → 5.2.1
- .claude-plugin/marketplace.json: version 5.2.0 → 5.2.1
- plugin/.claude-plugin/plugin.json: version 5.2.0 → 5.2.1
- CLAUDE.md: version 5.2.0 → 5.2.1

All changes follow CLAUDE.md coding standards (DRY, YAGNI, fail-fast).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-mem",
-  "version": "5.2.0",
+  "version": "5.2.1",
   "description": "Persistent memory system for Claude Code - seamlessly preserve context across sessions",
   "author": {
     "name": "Alex Newman"