test(web): run isolated web suite directly

[tyler-dane]

Summary

Reduces web unit test runs from ~4min to under 1 minute.

This replaces the interim batched web test runner with the intended endpoint: bun run test:web now runs bun test --cwd packages/web directly, and the shared test dispatcher no longer walks or chunks web test files.

The branch keeps the previous batching commit as history, but the latest commit removes that workaround and fixes the underlying isolation leaks that forced batching/process boundaries in the first place.

What changed

• Removed web-specific batching from packages/scripts/src/testing/run.ts.
• Changed package.json so test:web is a direct Bun test command.
• Added render-with-store for web tests that should use real Redux providers instead of mocking store hooks.
• Reworked leaking web tests away from broad mock.module usage for shared modules and UI primitives.
• Added small dependency factories for hard-to-isolate hooks/utilities instead of mocking production modules process-wide.
• Tightened web preload cleanup for DOM/storage/MSW/browser state and sanitized the JSDOM-hostile datepicker :has(...) styled-components rule without deleting unrelated styles.
• Updated the testing playbook with web isolation rules and direct-suite acceptance criteria.

Why the interim batching approach was a smell

Batching made the suite faster than one-file-per-process execution, but it still encoded test isolation into packages/scripts/src/testing/run.ts instead of into the tests themselves. That meant:

• the runner knew too much about web test file layout;
• WEB_TEST_BATCH_SIZE became a hidden compatibility contract;
• top-level mock.module leaks still depended on file order and process boundaries;
• broad child/store/session mocks could silently change later tests in the same Bun process;
• the desired command, bun test --cwd packages/web, still could not be trusted.

The real fix is to keep tests independent enough that Bun can run the package suite in one direct invocation.

Follow-up plan

The suite now meets the desired endpoint, but the remaining test hygiene work should continue in normal feature work:

1. Prefer real providers and renderWithStore over mocking Redux hooks or @web/store.
2. Avoid top-level mock.module for shared UI primitives, session hooks, and utility modules.
3. Use dependency factories only where the dependency is genuinely hard to control through providers or public APIs.
4. Restore any replaced globals in teardown.
5. Treat bun test --cwd packages/web as the acceptance check for web isolation, not just focused file runs.

Verification

• bun test --cwd packages/web passes: 1029 tests.
• bun run test:web passes: 1029 tests.
• bun run type-check:web-tests passes.
• bun run type-check passes.
• bun lint passes.
• bun run test:scripts passes: 57 tests.