Fix/skill zip symlink resolution (#1040)

* fix(skill): resolve symlinks in ZIP extraction for GitHub repos (#1001)

- detect symlink entries via is_symlink() during ZIP extraction and collect target paths

- add resolve_symlinks_in_dir() to copy symlink target content into link location

- canonicalize base_dir to fix macOS /tmp → /private/tmp path comparison issue

- add path traversal safety check to block symlinks pointing outside repo boundary

- apply symlink resolution to both download_and_extract and extract_local_zip paths

Closes https://github.com/farion1231/cc-switch/issues/1001

* fix(skill): change search to match name and repo instead of description

* feat(skill): support importing skills from ~/.agents/skills/ directory

- Scan ~/.agents/skills/ in scan_unmanaged() for skill discovery
- Parse ~/.agents/.skill-lock.json to extract repo owner/name metadata
- Auto-add discovered repos to skill_repos management on import
- Add path field to UnmanagedSkill to show discovered location in UI

Closes #980

* fix(skill): use metadata name or ZIP filename for root-level SKILL.md imports (#1000)

When a ZIP contains SKILL.md at the root without a wrapper directory,
the install name was derived from the temp directory name (e.g. .tmpDZKGpF).
Now falls back to SKILL.md frontmatter name, then ZIP filename stem.

* feat(skill): scan ~/.cc-switch/skills/ for unmanaged skill discovery and import

* refactor(skill): unify scan/import logic with lock file skillPath and repo saving

- Deduplicate scan_unmanaged and import_from_apps using shared source list
- Replace hand-written AppType match with as_str() and AppType::all()
- Extract read_skill_name_desc, build_repo_info_from_lock, save_repos_from_lock helpers
- Add SkillApps::from_labels for building enable state from source labels
- Parse skillPath from .skill-lock.json for correct readme URLs
- Save skill repos to skill_repos table in both import and migration paths

* fix(skill): resolve symlink and path traversal issues in ZIP skill import

* fix(skill): separate source path validation and add canonicalization for symlink safety

src/i18n/locales/en.json

@@ -1322,7 +1322,7 @@
       "skillCount": "{{count}} skills detected"
     },
     "search": "Search Skills",
-    "searchPlaceholder": "Search skill name or description...",
+    "searchPlaceholder": "Search skill name or repo...",
     "filter": {
       "placeholder": "Filter by status",
       "all": "All",

src/i18n/locales/ja.json

@@ -1320,7 +1320,7 @@
       "skillCount": "{{count}} 件のスキルを検出"
     },
     "search": "スキルを検索",
-    "searchPlaceholder": "スキル名または説明で検索...",
+    "searchPlaceholder": "スキル名またはリポジトリで検索...",
     "filter": {
       "placeholder": "状態で絞り込み",
       "all": "すべて",

src/i18n/locales/zh.json

@@ -1322,7 +1322,7 @@
       "skillCount": "识别到 {{count}} 个技能"
     },
     "search": "搜索技能",
-    "searchPlaceholder": "搜索技能名称或描述...",
+    "searchPlaceholder": "搜索技能名称或仓库名称...",
     "filter": {
       "placeholder": "状态筛选",
       "all": "全部",