refactor(qa): keep synthetic UX evidence out of scenario catalog (#109315)

* refactor(qa): keep UX evidence producer out of catalog

* test(qa): preserve UX producer runner integration

qa/scenarios/ui/ux-matrix-evidence-dashboard.yaml

@@ -1,35 +0,0 @@
-title: UX Matrix evidence dashboard
-
-scenario:
-  id: ux-matrix-evidence-dashboard
-  surface: control-ui
-  category: browser-control-ui-and-webchat.browser-ui
-  coverage:
-    primary:
-      - qa.artifact-safety
-    secondary:
-      - ui.control
-      - gateway.control-ui-hosting
-      - cli.entrypoint
-      - cli.status-snapshots
-      - tools.evidence
-      - workspace.artifacts
-  objective: Produce UX Matrix evidence artifacts through the QA Lab script producer contract.
-  successCriteria:
-    - The script producer writes manifest.json, matrix.json, release-ledger.json, scorecard.md, latest-run.json, and qa-evidence.json.
-    - Evidence entries declare coverage IDs and artifact paths for generated logs, screenshot proof, and video-style proof.
-    - Missing local browser or CLI prerequisites are represented as blocked evidence with logs instead of fake artifacts.
-  docsRefs:
-    - docs/concepts/qa-e2e-automation.md
-    - docs/web/control-ui.md
-  codeRefs:
-    - scripts/qa/ux-matrix-evidence-producer.ts
-    - extensions/qa-lab/src/test-file-scenario-runner.ts
-  execution:
-    kind: script
-    path: scripts/qa/ux-matrix-evidence-producer.ts
-    summary: Script-backed UX Matrix producer that emits QA Lab evidence artifacts.
-    allowBlockedEvidence: true
-    args:
-      - --artifact-base
-      - ${outputDir}