ADR-013 Phase 4: relocate 4 self-contained plugin frontends

Relocate applications, geenforce, knowledgebase, and machines - each owns only
its own views dir, so a clean move to plugins/<name>/frontend/ (views/ +
routes.js, core imports rewritten to @/). geenforce's entryForm.js helper + its
vitest spec move with it (ManifestEditor imports it as a sibling).

Machinery fixes this batch surfaced:
- routes.gen.js codegen uses namespace imports (import * as p_x). A route file
  without a `toplevel` export is undefined on the namespace instead of a strict-
  ESM missing-binding build error.
- vitest gains a `pretest` stage so plugin-frontend specs (now under
  plugins/<name>/frontend/) run from their staged copy in src/.plugins-staged/.

Verified live: GE-Enforce (the most complex, uses the entryForm sibling helper)
renders fully from its staged frontend. Build + 58 vitest + naming green.

frontend/package.json

@@ -10,6 +10,7 @@
     "prebuild": "npm run stage",
     "build": "vite build",
     "preview": "vite preview",
+    "pretest": "npm run stage",
     "test": "vitest run",
     "test:watch": "vitest"
   },