devops: extract reusable PR CI triage workflow

[Skn0tt]

Pulls the Copilot CI-failure triage out of create_test_report.yml into
.github/workflows/pr-ci-triage.yml so other repos (playwright-browsers
roll PRs) can call it via workflow_call. Behaviour for this repo should
be unchanged - same prompt, same comment posting, just one pr_number
input.

[github-actions]

Test results for "tests 1"

10 flaky

⚠️ [chromium-library] › library/video.spec.ts:736 › screencast › should work with video+trace `@frozen-time-library-chromium-linux`
⚠️ [chromium-library] › library/video.spec.ts:294 › screencast › should capture navigation `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/video.spec.ts:664 › screencast › should capture full viewport `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/video.spec.ts:294 › screencast › should capture navigation `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-library] › library/video.spec.ts:736 › screencast › should work with video+trace `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-library] › library/browsertype-connect.spec.ts:984 › run-server › socks proxy › should proxy requests from fetch api over ipv6 `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/defaultbrowsercontext-1.spec.ts:89 › should support viewport option `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-page] › page/page-event-request.spec.ts:181 › should return response body when Cross-Origin-Opener-Policy is set `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-page] › page/page-goto.spec.ts:90 › should work with Cross-Origin-Opener-Policy `@firefox-ubuntu-22.04-node20`
⚠️ [webkit-page] › page/page-set-input-files.spec.ts:38 › should upload a folder `@webkit-ubuntu-22.04-node20`

51109 passed, 1188 skipped

---

Merge workflow run.

[github-actions]

Test results for "MCP"

2 failed
❌ [firefox] › mcp/cli-core.spec.ts:106 › fill numeric @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-core.spec.ts:216 › dialog-accept @mcp-windows-latest-firefox

7865 passed, 1272 skipped

---

Merge workflow run.

[github-actions]

🟢 The PR is clear — the two failures are pre-existing Windows-Firefox flakes

Hi, I'm the Playwright bot and I took a first look at the CI failures here.

This PR only edits CI workflow YAML (create_test_report.yml, pr-ci-triage.yml) — no product or test code. The two failing MCP tests both flake on mcp-windows-latest-firefox on unrelated SHAs, so nothing here points back to your change.

Details

Overall: the latest merged report is the MCP run (run 30830733896) with 2 failures, both on mcp-windows-latest-firefox. The "tests 1" run alongside it was green (10 flaky, 0 failed). The diff touches only .github/workflows/*, which the MCP CLI tests don't exercise.

Pre-existing flake / infra

• [firefox] › mcp/cli-core.spec.ts:216 › dialog-accept <prompt> — flaky, isolated to Windows Firefox. Across the test-results DB it failed 14 of 334 runs (4.2%) and passed the other 320 on mcp-windows-latest-firefox, on SHAs unrelated to this PR; 0 failures on every other bot/OS.
• [firefox] › mcp/cli-core.spec.ts:106 › fill numeric — flaky. Failed 1 of 335 runs on mcp-windows-latest-firefox and 1 of 580 on mcp-macos-latest-chromium, passing everywhere else — a rare, cross-SHA flake, not something a workflow-YAML change could cause.

_{Triaged by the Playwright bot - agent run}