Release v5.1.2: Add theme toggle for light/dark mode

Features:
- Theme toggle functionality with light, dark, and system preferences
- User-selectable theme with persistent settings
- Automatic system preference detection

Technical changes:
- Updated viewer UI with theme toggle controls
- Version bump across all metadata files (5.1.1 → 5.1.2)
- Rebuilt all plugin scripts

🤖 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": "5.1.1",
+  "version": "5.1.2",
   "description": "Persistent memory system for Claude Code - seamlessly preserve context across sessions",
   "author": {
     "name": "Alex Newman"