chore(release): bump version to v3.7.0 and rebrand to include Gemini CLI

- Update version from 3.6.2 to 3.7.0 across all config files
- Update project description to "All-in-One Assistant for Claude Code, Codex & Gemini CLI"
- Update Chinese description to "Claude Code / Codex / Gemini CLI 全方位辅助工具"
- Sync version in package.json, Cargo.toml, tauri.conf.json
- Update branding in README.md, README_ZH.md and i18n locale files

src/i18n/locales/en.json

@@ -1,7 +1,7 @@
 {
   "app": {
     "title": "CC Switch",
-    "description": "Claude Code & Codex Provider Switching Tool"
+    "description": "All-in-One Assistant for Claude Code, Codex & Gemini CLI"
   },
   "common": {
     "add": "Add",

src/i18n/locales/zh.json

@@ -1,7 +1,7 @@
 {
   "app": {
     "title": "CC Switch",
-    "description": "Claude Code & Codex 供应商切换工具"
+    "description": "Claude Code / Codex / Gemini CLI 全方位辅助工具"
   },
   "common": {
     "add": "添加",