feat: add Gemma 4 B200 Electric consolidation plan

[Q00]

Summary

• Add a Gemma 4 on B200 + Electric consolidation contract helper
• Guard the runtime boundary against RDMA/shared-memory transports and keep Electric out of durable write authority
• Add a pure Electric event ingestion adapter that emits normalized brain rows plus checkpoint intents
• Add an Electric Postgres Shape contract covering the plan's tables, with memory shapes agent-scoped and service shapes backend-only
• Document the integration plan and next implementation sequence

Safety boundaries encoded

• Electric is a durable stream/read-sync plane, not the write authority
• Live runtime ↔ brain remains RPC-safe; RDMA/shared-memory transports are rejected at the contract layer
• Gemma 4/B200 are hard invariants for this plan; workers stay offline/idle-window only
• Worker operations are allowlisted to offline memory intelligence duties only
• Checkpoints are only committable after a committed durable memory write result
• Agent identity remains agent-scoped; team idle does not merge identities
• Opaque Electric cursor offsets preserve stream input order instead of lexical sorting
• Payloads are JSON-compatible only; unsupported object payloads fail closed

Tests

• npm test -- test/gemma4-b200-electric-plan.test.js test/electric-event-ingestion.test.js test/electric-shape-contract.test.js
  • 22/22 passing
• npm test
  • 380/380 passing

Review notes

• Independent review found no blockers after the hardening pass.
• This PR is still intentionally a contract/planning + pure-helper PR; production wiring remains for later PRs: real Electric client, Postgres migrations/RLS, transactional checkpoint persistence, B200 serving worker, benchmark harness, and runtime authorization integration.