feat(ui): add page title context

[casey-brooks]

Summary

• add PageTitleContext and useDocumentTitle hook for dynamic header titles
• update org/agent pages to use page titles and remove top-level headings
• align E2E selectors and add PageTitleContext unit coverage

Testing

• npm run lint
• npm run typecheck
• npm test
• npm run build

Closes #33

[casey-brooks]

Summary

• added PageTitleContext/useDocumentTitle to drive the AppLayout header
• removed page-level headings across org/agent pages in favor of the shared title
• updated E2E selectors and added PageTitleContext unit coverage

Testing

• npm run lint (no errors)
• npm run typecheck
• npm test (31 passed)
• npm run build

[casey-brooks]

Testing

• npm run lint (no errors)
• npm run typecheck
• npm test (31 passed, 0 failed, 0 skipped)
• npm run build

[rowan-stein]

CI Status

• ✅ build — passed (lint, typecheck, tests, build)
• ✅ e2e — passed (12m34s)
• ⚠️ argos — 12 changed screenshots, waiting for approval

The Argos visual diffs are expected — we removed page-level headers from all pages, so every screenshot that included a heading will show a visual difference. These need manual approval in the Argos dashboard.

Requesting code review.

[noa-lucent]

Overall the PR is well-structured and consistent — the context split, hook pattern, and page-level changes all align with the spec and existing codebase conventions. Clean work.

Three items to address:

1. [major] Missing useDocumentTitle unit test — the issue spec requires test case 4 covering mount-time title setting and updates on prop change.
2. [minor] OrganizationDetailLayout retains a full getOrganization query whose data is no longer consumed — consider removing it.
3. [minor] OrganizationMonitoringTab has a redundant nested space-y-6 div wrapper after heading removal — flatten it.

[casey-brooks]

Summary

• added useDocumentTitle hook coverage with rerender assertions
• removed unused org detail query and simplified monitoring layout wrapper

Testing

• npm run lint (no errors)
• npm run typecheck
• npm test (32 passed, 0 failed, 0 skipped)
• npm run build

[noa-lucent]

All three items verified in code and resolved:

1. ✅ useDocumentTitle test added — covers mount-time title setting and re-render updates via DocumentTitleProbe.
2. ✅ OrganizationDetailLayout cleaned up — unused orgQuery, useQuery, useParams, and organizationsClient imports removed. Minimal wrapper now.
3. ✅ OrganizationMonitoringTab flattened — redundant nested space-y-6 div eliminated.

PR fully resolves #33. Clean, consistent, well-tested. Good to merge.