feat(db): CMP-1 persist durable custom agents

[ripgrim]

Summary

Adds the durable persistence and API domain for custom agents: definitions, immutable versions, triggers, runs, actions, audit records, conversation submissions, attachments, sharing, feedback, and access control.

Why

Custom agents need a durable, permission-aware lifecycle before the builder UI or runtime can rely on them.

Stack

Targets main through this pull request only.

1. #59 — durable custom-agent domain
2. #60 — sandboxed builder and runner runtimes
3. #61 — CRM UI foundations
4. #62 — private agent-builder workspace
5. #63 — pre-deployment draft review
6. #64 — builder presentation
7. #65 — inline composer context

Verification

• Full typecheck passes
• Lint passes
• Database-backed suites require DATABASE_URL

[vercel]

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[ripgrim]

Superseded by the all-upstream native stack rooted at #67.