test(FN-2358): harden clean-worktree CI verification tests

- Assert contributing docs explicitly state that pnpm test must run without prior build outputs
- Add CI workflow test coverage to keep docs and verify:workspace ordering aligned
- Expand Vitest workspace alias assertions to include @fusion/test-utils and src-only replacements
- Validate real symbol imports from workspace packages when dist directories are absent

docs/contributing.md

@@ -55,6 +55,7 @@ pnpm typecheck         # workspace typechecks
 Fusion codifies workspace verification as a deterministic contract:
 
 - `pnpm test` must be runnable in a clean worktree without requiring a prior `pnpm build`.
+- This includes clean states where `packages/core/dist`, `packages/engine/dist`, and `packages/dashboard/dist` are absent.
 - `pnpm verify:workspace` is the canonical pre-merge gate and runs in strict order:
   1. `pnpm lint`
   2. `pnpm test`