chore(release): prepare for v3.6.1 release

- Bump version to 3.6.1 across all config files
  - package.json, Cargo.toml, tauri.conf.json
  - README.md and README_ZH.md version badges
  - Auto-updated Cargo.lock
- Add release notes documentation
  - docs/release-note-v3.6.0-en.md (archive)
  - docs/release-note-v3.6.1-zh.md (cumulative format)
  - docs/release-note-v3.6.1-en.md (cumulative format)
- Enlarge PackyCode sponsor logo by 50% (100px → 150px)
- Update roadmap checklist (homebrew support marked as done)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "cc-switch",
-  "version": "3.6.0",
+  "version": "3.6.1",
   "description": "Claude Code & Codex 供应商切换工具",
   "scripts": {
     "dev": "pnpm tauri dev",