fix(extension): do not treat orphaned preferences entries as an installed extension

[Yury Semikhatsky (yury-s)]

Summary

• Uninstalling the extension leaves orphaned entries in the profile's Preferences (empty extensions.settings.<id> record, protection.macs.*, updateclientdata.apps.*) that matched the substring check, so the wrong profile could be launched.
• Require a populated extensions.settings.<id> record instead; also read Secure Preferences, where the record lives on Windows/macOS.

Fixes microsoft/playwright-mcp#1712

[github-actions]

Test results for "MCP"

2 failed
❌ [firefox] › mcp/cli-core.spec.ts:106 › fill numeric @mcp-windows-latest-firefox
❌ [firefox] › mcp/cli-devtools.spec.ts:115 › per-part commands extract individual parts @mcp-windows-latest-firefox

8093 passed, 1304 skipped

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Merge workflow run.

[github-actions]

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

🟢 Both failures are pre-existing Firefox flakes — the PR is clear

The two reds are MCP CLI tests on mcp-windows-latest-firefox, and neither touches the extension-install detection this PR changes. Both flip verdict across many unrelated runs.

Details

This PR only changes packages/playwright-core/src/tools/utils/extension.ts (how an installed extension is detected in a profile's Preferences) and the matching tests/extension/extension.spec.ts. The failing tests exercise the fill and per-part request CLI commands — unrelated code paths.

Pre-existing flake / infra

• [firefox] › mcp/cli-core.spec.ts:106 › fill numeric — cross-run flake on mcp-windows-latest-firefox. Over 725 runs it failed only twice (once was rescued on retry), and the other failure is on PR devops: extract reusable PR CI triage workflow #42090 — a SHA this PR can't be responsible for. Passed 724/725.

• [firefox] › mcp/cli-devtools.spec.ts:115 › per-part commands extract individual parts — cross-run flake on the same bot. Failed 3 of 725 runs (2 more rescued on retry) on SHAs from PRs chore: mark v1.62.1 #42020, chore: remove experimental component testing #42168, feat(trace-viewer): show test annotations in the trace viewer #42060 and a main push — all unrelated to this change. Passed 722/725.

Both are Firefox/Windows-only, in code the PR never touches, with a long history of the same failures elsewhere. No evidence points at this PR.

_{Triaged by the Playwright bot - agent run}