chore: bump version to v3.1.1

- Update version in package.json, Cargo.toml, and tauri.conf.json
- Add CHANGELOG entries for v3.1.0 and v3.1.1

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "CC Switch",
-  "version": "3.0.0",
+  "version": "3.1.1",
   "identifier": "com.ccswitch.desktop",
   "build": {
     "frontendDist": "../dist",