feat: add project profiles for snapshot-based config switching

Add a profile feature that captures the current provider, MCP,
skills and prompt state for Claude Code and Codex as a named
snapshot, and re-applies it in one click from the header switcher
or the tray Projects submenu.

- New profiles table (schema v12) with current marker in settings
- ProfileService orchestrates the four existing switch primitives
  (provider first, then MCP diff, skills diff, prompt enable)
- Best-effort apply: dangling references become warnings, no rollback
- Header combobox switcher + snapshot-style manage dialog
- Tray Projects submenu shared with the UI apply/event pipeline
- i18n for zh/en/ja/zh-TW under the new profiles domain
- Integration tests covering roundtrip, dangling refs and clear

src-tauri/src/services/mod.rs

@@ -7,6 +7,7 @@ pub mod env_manager;
 pub mod mcp;
 pub mod model_fetch;
 pub mod omo;
+pub mod profile;
 pub mod prompt;
 pub mod provider;
 pub mod proxy;