build(frontend)!: knip drops --production; plain knip stays

The production pass (7ed2ac4e, E32) asked "is this export used by what
ships?". No real hit: its only findings were 37 exports a test imports,
answered with 36 `@internal` JSDoc tags (E34 S2) — test-only exports, not
defects. Since then it has only ever asked for another tag. The tags go
with it (36, no longer read by anything), and so do the production-only
`!…!` exclusions in knip.jsonc and their register rows. Plain knip (unused
files, exports and dependencies) keeps running in the gate.

frontend/package.json

@@ -14,7 +14,7 @@
     "typecheck:e2e": "tsc --noEmit -p e2e/tsconfig.json",
     "build": "npm run typecheck:app && npm run typecheck:node && vite build",
     "preview": "vite preview",
-    "knip": "knip && knip --production",
+    "knip": "knip",
     "lint": "eslint . --max-warnings 0",
     "format": "prettier --write .",
     "format:check": "prettier --check .",