Adopt database-fenced source and angle claims

[OneClickPostFactory]

Purpose

Promote D04/D05/D06 atomic source and angle claims after upstream PR #5. Publication-ledger execution follows separately.

Base and head

Base: upstream main after #5, c1e780a.
Head: 9650518.
Zero commits behind; seven-file claims-only diff. Synchronisation preserved the previously tested code tree unchanged.

Changes

• Caller-owned claim tokens, expiring leases and monotonic fencing before paid source/angle work.
• Atomic, idempotent source-to-angle and angle-to-queue finalisation.
• No automatic regeneration when durable finalisation is uncertain.
• Single-attempt ambiguous ordinary Supabase mutations; retries only for reads and explicitly idempotent RPCs.
• Require worker-claims-v1 for generation without gating already-prepared publishing on that capability.

Evidence

Fresh fork CI #82 passed the full npm run ci gate on the exact head:
https://github.com/AyobamiH/social-agents/actions/runs/34135248264

Upstream PR CI must also pass before merge. Paired schema source is already merged and locally database-tested; production schema application is not claimed.

Boundaries and merge order

Manual-only deployment guard from #5 is unchanged. No deploy, production migration, provider re-enable or live social post. Reddit connector ownership and local scheduling remain unchanged.
This is not the publication-ledger executor or completion of all duplicate-publication repairs.
Order: #5 (merged), this claims PR, then publication-ledger executor.
Use Create a merge commit after upstream CI passes. Keep the source branch for dependent work. Schema-first staging, legacy drain and canaries remain separate rollout gates.