chore(release): prepare v3.16.3

- Bump version to 3.16.3 (package.json, tauri.conf.json, Cargo.toml, Cargo.lock)
- Add CHANGELOG entry for v3.16.3 (59 commits since v3.16.2)
- Add trilingual release notes (zh / en / ja) under docs/release-notes/

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cc-switch",
-  "version": "3.16.2",
+  "version": "3.16.3",
   "description": "All-in-One Assistant for Claude Code, Codex & Gemini CLI",
   "type": "module",
   "scripts": {