Add durable workstream memory across conversations

[fmhall]

Summary

OpenInstinct can retain an ongoing undertaking across conversations: its goal, constraints, decisions, source-linked observations, and unresolved next step. The agent reads the current record before resuming or updating it, so a correction made in one conversation remains available in the next.

This uses Eve's native memory-provider lifecycle, locked memory scope, recalled-message supersession, and replayable tools. The application database owns structured records, search, revision checks, and deletion tombstones. The access checks for slot activation, recall, and tools share one implementation.

• Available only to interactive authenticated root turns; no implicit scheduling or authorization.
• Recalls the eight most recently updated active/waiting summaries; older and completed records remain searchable.
• Allows up to 100 records with saved content per scope. Forgetting erases content and sources while retaining a tombstone to prevent delayed saves from restoring them.
• Adds one database table through the normal additive migration path. Vercel's existing build dependency runs migrations before deployment.

Updated against current main, including its upgraded Eve runtime. No further Eve dependency change or patch is introduced by this PR.

Validation

• pnpm check — 713 tests, types, lint, formatting, and Knip passed.
• pnpm build and pnpm exec eve build — passed.
• pnpm db:check — passed; real PostgreSQL eval setup also applied all migrations.
• Live model evals on the final source — 2 cases, 20 gates passed. Verified save, correction, recall/read in a fresh session, forgetting, and no workstream creation for a one-off question. Each run used an isolated disposable database; no production records were changed.