Feat/claude skills management (#237)

* feat(skills): add Claude Skills management feature

Implement complete Skills management system with repository discovery,
installation, and lifecycle management capabilities.

Backend:
- Add SkillService with GitHub integration and installation logic
- Implement skill commands (list, install, uninstall, check updates)
- Support multiple skill repositories with caching

Frontend:
- Add Skills management page with repository browser
- Create SkillCard and RepoManager components
- Add badge, card, table UI components
- Integrate Skills API with Tauri commands

Files: 10 files changed, 1488 insertions(+)

* feat(skills): integrate Skills feature into application

Integrate Skills management feature with complete dependency updates,
configuration structure extensions, and internationalization support.

Dependencies:
- Add @radix-ui/react-visually-hidden for accessibility
- Add anyhow, zip, serde_yaml, tempfile for Skills backend
- Enable chrono serde feature for timestamp serialization

Backend Integration:
- Extend MultiAppConfig with SkillStore field
- Implement skills.json migration from legacy location
- Register SkillService and skill commands in main app
- Export skill module in commands and services

Frontend Integration:
- Add Skills page route and dialog in App
- Integrate Skills UI with main navigation

Internationalization:
- Add complete Chinese translations for Skills UI
- Add complete English translations for Skills UI

Code Quality:
- Remove redundant blank lines in gemini_mcp.rs
- Format log statements in mcp.rs

Tests:
- Update import_export_sync tests for SkillStore
- Update mcp_commands tests for new structure

Files: 16 files changed, 540 insertions(+), 39 deletions(-)

* style(skills): improve SkillsPage typography and spacing

Optimize visual hierarchy and readability of Skills page:
- Reduce title size from 2xl to lg with tighter tracking
- Improve description spacing and color contrast
- Enhance empty state with better text hierarchy
- Use explicit gray colors for better dark mode support

* feat(skills): support custom subdirectory path for skill scanning

Add optional skillsPath field to SkillRepo to enable scanning skills
from subdirectories (e.g., "skills/") instead of repository root.

Changes:
- Backend: Add skillsPath field with subdirectory scanning logic
- Frontend: Add skillsPath input field and display in repo list
- Presets: Add cexll/myclaude repo with skills/ subdirectory
- Code quality: Fix clippy warnings (dedup logic, string formatting)

Backward compatible: skillsPath is optional, defaults to root scanning.

* refactor(skills): improve repo manager dialog layout

Optimize dialog structure with fixed header and scrollable content:
- Add flexbox layout with fixed header and scrollable body
- Remove outer border wrapper for cleaner appearance
- Match SkillsPage design pattern for consistency
- Improve UX with better content hierarchy

src/lib/api/skills.ts

@@ -0,0 +1,47 @@
+import { invoke } from "@tauri-apps/api/core";
+
+export interface Skill {
+  key: string;
+  name: string;
+  description: string;
+  directory: string;
+  readmeUrl?: string;
+  installed: boolean;
+  repoOwner?: string;
+  repoName?: string;
+  repoBranch?: string;
+}
+
+export interface SkillRepo {
+  owner: string;
+  name: string;
+  branch: string;
+  enabled: boolean;
+  skillsPath?: string; // 可选：技能所在的子目录路径，如 "skills"
+}
+
+export const skillsApi = {
+  async getAll(): Promise<Skill[]> {
+    return await invoke("get_skills");
+  },
+
+  async install(directory: string): Promise<boolean> {
+    return await invoke("install_skill", { directory });
+  },
+
+  async uninstall(directory: string): Promise<boolean> {
+    return await invoke("uninstall_skill", { directory });
+  },
+
+  async getRepos(): Promise<SkillRepo[]> {
+    return await invoke("get_skill_repos");
+  },
+
+  async addRepo(repo: SkillRepo): Promise<boolean> {
+    return await invoke("add_skill_repo", { repo });
+  },
+
+  async removeRepo(owner: string, name: string): Promise<boolean> {
+    return await invoke("remove_skill_repo", { owner, name });
+  },
+};