chore(extension): typecheck extension as part of lint

[Dmitry Gozman (dgozman)]

Summary

• npm run tsc (and so lint/flint) now also runs the two packages/extension tsconfigs, which the root tsconfig excludes.
• Fix the existing extension type errors after the @types/chrome bump: TabChangeInfo -> OnUpdatedInfo, and ungroupTabs() passes a non-empty tuple.

Fixes #43050

[github-actions]

Test results for "tests 1"

7 flaky

⚠️ [chromium-library] › library/browsercontext-page-event.spec.ts:160 › should work with Shift-clicking `@chromium-ubuntu-22.04-arm-node20`
⚠️ [chromium-library] › library/chromium/chromium.spec.ts:179 › serviceWorker(), and fromServiceWorker() work `@realtime-time-library-chromium-linux`
⚠️ [chromium-library] › library/browsercontext-page-event.spec.ts:173 › should work with Ctrl-clicking `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-library] › library/tracing.spec.ts:533 › should produce screencast frames fit `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:257 › third party 'Partitioned;' cookies `@firefox-ubuntu-22.04-node20`
⚠️ [firefox-library] › library/browsercontext-cookies-third-party.spec.ts:470 › top level 'Partitioned;' cookie and same origin iframe `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145 › should watch all `@ubuntu-latest-node26`

52536 passed, 1270 skipped

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Merge workflow run.

[github-actions]

Test results for "MCP"

8937 passed, 1489 skipped

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Merge workflow run.