feat(03-01): add skill section type wiring, Zustand slice, i18n, and sidebar nav entry

- Add "skills" to SectionId union in shared types
- Add SkillRecord, SkillImportResult, SkillUpdateStatus types to shared/types.ts
- Create SkillSlice with skills list, selection, file path, and import modal state
- Wire SkillSlice into Zustand store composition
- Add "nav.skills" i18n keys for English and Chinese
- Add Skills sidebar nav entry with PuzzlePiece icon between Communication and Documents
- Add section === "skills" rendering route in App.tsx
- Clear skill state on company switch
- Add skills case to navigateTo in NavigationSlice

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/shared/types.ts

@@ -16,6 +16,7 @@ export type SectionId =
   | "activity"
   | "workspaces"
   | "social"
+  | "skills"
   | "automation"
   | "communication"
   | "documents"
@@ -453,6 +454,50 @@ export interface OnboardingBootstrapResult {
   runId: string | null;
 }
 
+// ── Skill types ──
+
+export type SkillSourceType = "github" | "local_path" | "url" | "skills_sh" | "managed";
+export type TrustLevel = "markdown_only" | "assets" | "scripts_executables";
+
+export interface FileInventoryEntry {
+  path: string;
+  kind: "skill" | "reference" | "script" | "asset" | "markdown" | "other";
+}
+
+export interface SkillRecord {
+  id: string;
+  companyId: string;
+  key: string;
+  slug: string;
+  name: string;
+  description: string | null;
+  markdown: string;
+  sourceType: SkillSourceType;
+  sourceLocator: string | null;
+  sourceRef: string | null;
+  trustLevel: TrustLevel;
+  compatibility: string;
+  fileInventory: FileInventoryEntry[];
+  metadata: Record<string, unknown> | null;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface SkillImportResult {
+  skillId: string;
+  key: string;
+  name: string;
+  isUpdate: boolean;
+}
+
+export interface SkillUpdateStatus {
+  skillId: string;
+  key: string;
+  currentRef: string | null;
+  latestRef: string | null;
+  hasUpdate: boolean;
+}
+
 export type SocialPlatform = "twitter" | "linkedin" | "instagram" | "facebook" | "reddit" | "youtube" | "tiktok" | "bluesky" | "other";
 export type SocialAccountStatus = "active" | "logged_in" | "login_required" | "suspended" | "paused";
 export type BrowserActionType = "post" | "reply" | "like" | "follow" | "browse_feed" | "screenshot" | "navigate" | "search";