perf(coding-agent): ~500x faster session parsing

- Replaced crypto.randomUUID() with nanoid() for ID generation across session-manager and rpc-mode.
- Added RecentSessionInfo class with lazy getters for fullName, name, and timeAgo properties.
- Simplified session retrieval by consolidating isValidSessionFile() into getSortedSessions() helper.
- Added nanoid ^5.1.6 dependency and removed duplicate safe-buffer entries from lockfile.

packages/coding-agent/package.json

@@ -52,6 +52,7 @@
 		"highlight.js": "^11.11.1",
 		"marked": "^15.0.12",
 		"minimatch": "^10.1.1",
+		"nanoid": "^5.1.6",
 		"node-html-parser": "^6.1.13",
 		"smol-toml": "^1.6.0",
 		"strip-ansi": "^7.1.2",