flagon-io/g1t

Part of #304. This PR does not close it.

The Library

• Name and address: the app that was Artifacts is now Library, at /<ws>/-/library/artifacts, the same naming Muse uses. -/library itself opens on its artifacts.
• Sidebar: it opens with an Artifacts group (All artifacts, Templates).
• Old addresses keep working:
  • Pages under -/artifacts/… redirect (308) to the same place in the Library, with their query. A 308 keeps the method, so a form posted from a page opened before the deploy still lands.
  • The live socket, API, threads, upload and export endpoints answer at both addresses. Pages already open keep working.
  • linkedArtifacts and the live-socket check accept both forms. Links pasted into chat before the move still count.
• Server-side links: the artifacts service, the API's html_url and the MCP descriptions all use the new address.
• Generated files: the API reference and the docs' OpenAPI copy are regenerated (G1T_WRITE_OPENAPI=1).

Sessions move to Chat

Chat becomes where people and agents both are.

• Chat's sidebar now starts with Needs attention, then a Sessions section with every view Work's had: Live now, Every session, Yours, and each kind.
• Address: sessions are now at -/chat/sessions and -/chat/sessions/:id. -/work/sessions… redirects there with its filters.
• Reserved name: sessions is added to Chat's reserved names, so no channel can take it.
• Outsiders can still view session pages. These pages sit outside Chat's layout, which requires sign-in and refuses non-members. So the Chat sidebar now loads its own data there (useChatSidebar(home)).
• Mobile app: it opens links to both addresses.

Smaller fixes

• New work item: the pill has room above the plan.
• Workspace menu: it now holds only the workspace and switching. Your profile and Your settings are in the account menu.
• Docs: they point at the Library and Chat's sessions, and describe the app bar where they still described the rail.

Checks

• tsc is clean.
• Tests pass: 1,172 web, 15 mobile link tests, 131 artifacts, 92 chat, 50 contracts.
• Rust tests for g1t-api, g1t-integrations and g1t-contracts pass.
• Build: all 291 routes load, and the deploy check passes.
• The docs site builds.
• Prettier is clean.
• I checked the Library, Work, Chat with sessions, the workspace menu and the new breadcrumbs in light and dark in a scratch harness.