refactor(profiles): shared project entity with per-scope switching

Projects are now global shared entities; Claude and Codex groups switch
independently via scoped current pointers and scoped payload slots.

- Remove scope column from profiles; keep current_profile_id_<scope>
- Use Option<Vec<String>> for mcp/skills to distinguish 'never captured'
  from 'captured empty', preventing cross-side accidental disable
- Update/apply operations scoped to the active group via merge_scope_from
- Tray menu nests same shared list under Claude Code/Codex groups
- Add i18n for per-scope tooltips and 'not saved for this side' hint

Refs: profile P1 shared-entity redesign

src-tauri/src/lib.rs

@@ -54,7 +54,7 @@ pub use mcp::{
 pub use prompt::Prompt;
 pub use provider::{Provider, ProviderMeta};
 pub use services::{
-    profile::{ProfilePayload, ProfileService},
+    profile::{ProfilePayload, ProfileScope, ProfileService},
     skill::{migrate_skills_to_ssot, ImportSkillSelection},
     ConfigService, EndpointLatency, McpService, PromptService, ProviderService, ProxyService,
     SkillService, SpeedtestService,