fix(registry): evaluate defaultCacheDirectory lazily

[dcrousso]

defaultCacheDirectory used to be computed inside the PLAYWRIGHT_BROWSERS_PATH branch of registryDirectory, so setting that variable skipped the platform check

#39423 hoisted it into an eagerly evaluated module constant, so it now throws Unsupported platform: <platform> at import, before registryDirectory consults PLAYWRIGHT_BROWSERS_PATH

this regressed setups that point PLAYWRIGHT_BROWSERS_PATH at their own browsers on platforms without a default cache directory, such as Android/Termux

evaluate defaultCacheDirectory, defaultRegistryDirectory, and baseDaemonDir lazily so an explicit PLAYWRIGHT_BROWSERS_PATH is honored before any default cache directory is computed

registryDirectory still throws eagerly when no override is set, since there is nowhere to place browsers

fixes #41852

[github-actions]

Test results for "MCP"

2 failed
❌ [chrome] › mcp/annotate.spec.ts:269 › should start dashboard and annotate when no dashboard is running @mcp-windows-latest-chrome
❌ [chromium] › mcp/cli-navigation.spec.ts:43 › tab-new with url @mcp-macos-latest-chromium

7784 passed, 1262 skipped

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Merge workflow run.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [chromium-library] › library/video.spec.ts:736 › screencast › should work with video+trace `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/popup.spec.ts:260 › should not throw when click closes popup `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-page] › page/page-goto.spec.ts:81 › should work with Cross-Origin-Opener-Policy `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:827 › should update state on subsequent run `@windows-latest-node22`

50213 passed, 1190 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 here.

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

The two MCP failures are known low-rate flakes on tests this PR doesn't touch. This PR only changes lazy evaluation of defaultCacheDirectory/registry paths, which the MCP annotate and tab-navigation flows don't exercise.

Details

Pre-existing flake / infra

• [chrome] › mcp/annotate.spec.ts:269 › should start dashboard and annotate when no dashboard is running — flake. In the test-results DB this test passes overwhelmingly and fails rarely across unrelated SHAs (e.g. 1 fail / 413 runs on chrome, 0 fails on 410 chromium / 403 firefox / 414 webkit runs), including a failure on the unrelated PR feat(test-runner): add httpCache config option #41687 where this branch can't be responsible.

• [chromium] › mcp/cli-navigation.spec.ts:43 › tab-new with url — flake. Same pattern: passes on the vast majority of runs and fails occasionally on unrelated SHAs (e.g. 2 fails / 413 chrome runs, 1 / 410 chromium, 0 on firefox/webkit), including a failure on the unrelated PR fix(webview): support input for elements inside cross-origin <iframe> #41463.

Neither test reaches the changed code: the diff is confined to registry/index.ts, serverRegistry.ts, cli-client/registry.ts, and browserFactory.ts (browser cache-directory resolution), plus a new browsers-path.spec.ts. The MCP dashboard/navigation paths don't depend on defaultCacheDirectory.

_{Triaged by the Playwright bot - agent run}