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/src/lib/gates.snapshot.json

@@ -2217,7 +2217,7 @@
       "e2e": "playwright test",
       "format": "prettier --write .",
       "format:check": "prettier --check .",
-      "knip": "knip && knip --production",
+      "knip": "knip",
       "lint": "eslint . --max-warnings 0",
       "preview": "vite preview",
       "test": "vitest run",
@@ -2313,7 +2313,7 @@
       "lane \"tsc (src + configs + e2e)\" frontend npm run --silent typecheck",
       "lane \"eslint (warnings fail too)\" frontend npm run --silent lint",
       "lane \"prettier --check\" frontend npm run --silent format:check",
-      "lane \"knip (unused, and unused by what ships)\" frontend npm run --silent knip",
+      "lane \"knip (unused files, exports, dependencies)\" frontend npm run --silent knip",
       "pytest_lane() { # the full suite against a throwaway Postgres; --pull keeps the base image current",
       "  docker compose -f \"$TESTCOMPOSE\" build --pull -q test || return 1",
       "  local rc=0",