fix(insights): suppress no-insight search-affordance misuse in tagger

Users routinely use the VIN-only /dashboard/search box to look for a part by
name (e.g. "Cam düğme") or fiddle with search/history and rage-click out of
affordance confusion — while nothing is actually broken. The generic
ux_friction / frustrated_session tags turned these pure-rage sessions into
insights (noise; ~40 of the first 67 open insights were exactly this, all
dismissed by the founder).

apps/worker/src/lib/tagger.ts: when a session used the search box
(search_input_focused) but carries NO concrete failure (errorCount=0,
network5xxCount=0, no vin_decode_failed, search_input_validation_failed<3, no
payment_initiated/failed, no checkout_started), do not emit the generic
ux_friction / frustrated_session tags. With no other actionable tag the session
becomes tag-less and tag-sessions discards it → no compress / analyze / insight.

Scoped narrowly to search-box sessions on purpose, to avoid hiding genuine
parts/category bugs. Every concrete signal stays actionable: JS errors
(bug_suspected), 5xx (server_error_impact), payment friction, VIN upstream
provider failures, and ≥3 client validation failures (search_validation_friction).

Smoke: apps/worker/src/lib/tagger.smoke.ts (12/12) covers the misuse case plus
six must-keep cases. tsc --noEmit clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/worker/package.json

@@ -6,7 +6,7 @@
     "dev": "tsx watch src/index.ts",
     "start": "tsx src/index.ts",
     "typecheck": "tsc --noEmit",
-    "test": "tsx src/lib/dedup.smoke.ts"
+    "test": "tsx src/lib/dedup.smoke.ts && tsx src/lib/tagger.smoke.ts"
   },
   "dependencies": {
     "@panel/web": "workspace:*",