feat: Phase 3 - Discovery Endpoints (stat and exists tools)

- Add stat tool for detailed file/folder metadata
- Add exists tool for fast path existence checking
- Add StatResult and ExistsResult type definitions
- Implement stat() and exists() methods in VaultTools
- Register both tools in ToolRegistry with complete schemas
- Update version to 2.1.0
- Update ROADMAP.md to mark Phase 3 complete
- Update CHANGELOG.md with Phase 3 release notes
- Add IMPLEMENTATION_NOTES_PHASE3.md documentation
- Clean up old phase documentation files

manifest.json

@@ -1,7 +1,7 @@
 {
 	"id": "obsidian-mcp-server",
 	"name": "MCP Server",
-	"version": "2.0.0",
+	"version": "2.1.0",
 	"minAppVersion": "0.15.0",
 	"description": "Exposes Obsidian vault operations via Model Context Protocol (MCP) over HTTP",
 	"isDesktopOnly": true