Adds the SQL substrate (6 tables + memory_status view) and the helpers
every user story depends on:
- migration 028_memory_consolidation.sql + smoke test
- internal/messaging/memory_config.go (env-flag plumbing)
- internal/messaging/dispatch_tokens.go (32-byte rand, 15m TTL, single-job-bound)
- internal/messaging/memory_channels.go (open-brain / reflections-* / is_memory flag)
- internal/agents/owner.go (OwnerFor with sentinel errors)
Deviations from spec, all documented in code:
- owner_id is stored as INTEGER FK to users; OwnerFor converts to the
string scope-key the new tables use.
- MemoryChannel is a local struct to avoid an import cycle between
internal/channels and internal/messaging.
- channels.metadata column does not exist yet; IsMemoryChannel honors
it conditionally so MemoryChannelIDs can extend trivially when added.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
