feat(FN-1968): add skill manifest previews to agent import

- Add SkillManifest support in core with parseSkillManifest and skills directory parsing/export wiring
- Extend /api/agents/import responses with dry-run skill previews and skillsCount metadata
- Show parsed package skills in AgentImportModal with dedicated preview UI and styles
- Add parser, API route, and modal tests covering skill manifest parsing and preview rendering
- Keep mission interview assertion generation explicit for milestone/slice fallbacks and update memory guidance for dashboard build resolution

.fusion/memory.md

@@ -307,7 +307,7 @@ Dashboard SSE (`/api/events`) streams plugin lifecycle events as normalized `plu
 - SQLite `ORDER BY timestamp DESC` alone can be nondeterministic when multiple rows share the same millisecond timestamp; add a stable tiebreaker (for example `rowid DESC`) when selecting a "latest" event.
 - In `TaskCard.tsx`, `isInteractiveTarget` must check `target instanceof Element` (not `HTMLElement`) so SVG elements from lucide-react icons are correctly detected as interactive when inside buttons.
 - If workspace tests fail resolving `@fusion/core` package exports from `packages/core/dist/index.js` (for example `No matching export ...` in CLI/TUI/package-level tests after adding a new core export), run `pnpm --filter @fusion/core build` before rerunning the suite so ignored `dist/` exports are refreshed.
-- If CLI tests fail resolving `@fusion/dashboard` (for example `Could not resolve "@fusion/dashboard"` in `build-exe` or command tests), build dashboard first with `pnpm --filter @fusion/dashboard build` so `packages/dashboard/dist/index.js` exists.
+- If CLI tests/build-exe tests fail with `Could not resolve "@fusion/dashboard"` (or Vite reports missing `@fusion/dashboard` entry), build the dashboard package first (`pnpm --filter @fusion/dashboard build`) so `packages/dashboard/dist/index.js` exists for workspace consumers.
 - QuickEntryBox control test IDs are reused in `ListView` integration tests; when control layout changes (for example nested menu → inline buttons), update both `QuickEntryBox.test.tsx` and `ListView.test.tsx` together to avoid cascading failures.
 - When `InlineCreateCard` layout changes, also check `Column.test.tsx` and `board-mobile.test.tsx` for references to moved/removed test IDs like `inline-create-description-actions`.
 - When adding portal-based dropdown menus to QuickEntryBox, tests may fail in isolation but pass when run together (test isolation issues). This is because tests share DOM state across describe blocks. Always verify new dropdown tests pass both in isolation (`--testNamePattern`) and when run together.