chore: Bump version to 0.9.3

Release highlights:
- Removed CGO dependency for better portability
- Fixed critical MCP server bugs (path resolution, init tool)
- Improved Claude Code plugin documentation
- Enhanced MCP server configuration robustness
- All 91 tests passing

Major changes since 0.9.2:
1. CGO removal - Pure Go SQLite driver for easier installation
2. MCP init fix - Tool now correctly creates .beads in current directory
3. MCP path resolution - Auto-detects bd executable via PATH
4. Plugin docs - Better quickstart for Claude Code users
5. Config validation - Command names resolved via shutil.which()

Breaking changes: None
Migration: No action needed

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

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

.claude-plugin/marketplace.json

@@ -9,7 +9,7 @@
       "name": "beads",
       "source": "./",
       "description": "AI-supervised issue tracker for coding workflows",
-      "version": "0.9.2"
+      "version": "0.9.3"
     }
   ]
 }

.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "beads",
   "description": "AI-supervised issue tracker for coding workflows. Manage tasks, discover work, and maintain context with simple CLI commands.",
-  "version": "0.9.2",
+  "version": "0.9.3",
   "author": {
     "name": "Steve Yegge",
     "url": "https://github.com/steveyegge"