fix(workbench): persist Pro conversation titles - #1273

Summary

Persist manual Pro conversation titles end to end so a rename survives reloads and cannot be rolled back by later owner-session status updates.

Related Issues

Fixes #1263

Changes

• Add a nullable agent_sessions.title column with an idempotent upgrade path and expose an additive AgentSessionTitleStore capability without changing AgentSessionStore.
• Add the missing owner-scoped PATCH /api/agent/sessions/:id route with strict validation, trim/120-character normalization, blank-to-null clearing, and uniform not-found behavior.
• Update the OwnerSessionClient authoritative snapshot during optimistic rename, server settle, and rollback; request one no-loading reconciliation after a changed successful write.
• Fence session-detail title bootstraps with a per-session revision so an older response cannot overwrite a rename or explicit clear made while it was in flight.
• Add real PGlite migration/isolation coverage, route boundary tests, and a shell regression test for the late status-event rollback race.
• Bump @openmaic/storage from 0.26.0 to 0.26.1.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/CD or build changes

Verification

Steps to reproduce / test

1. Rename a Pro conversation from the rail or attached header and reload the workspace.
2. Clear the title and verify the original prompt-derived fallback returns.
3. Deliver a later owner session_status update and verify it does not restore the previous title.
4. Delay the initial session-detail response, rename before it arrives, and compare the rail, attached header, and stored title after release.

What you personally verified

• Previous-head full verification: Node 22 package/dependency gates, Prettier, root TypeScript, i18n, ESLint, production build, root Vitest (7051 passed, 26 skipped), and package suites all passed.
• Current-head focused verification: all 77 workbench files passed (990 tests); root TypeScript, changed-file ESLint, Prettier, and diff checks passed.
• Manual browser verification against local PostgreSQL 16: rename + reload passed; clear + reload restored the prompt fallback.
• Deterministic delayed-response verification passed: after an older session-detail response carrying Race Start was captured, the title was changed to Race New; releasing the old response left the rail, attached header, and database on Race New. The same check passed for an explicit clear, preserving the prompt fallback instead of restoring the stale title.

Evidence

• Local verification results are summarized above; all four GitHub checks passed for the latest head.
• CI passes (pnpm check && pnpm lint && npx tsc --noEmit)
• Manually tested locally, including delayed session-detail responses during rename and clear
• Screenshots / recordings attached (if UI changes)

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have added/updated documentation as needed
• My changes do not introduce new warnings