[P3] Add tests for high-risk untested modules

[itsmiso-ai]

Problem

automation-sync.ts (382 lines, sync orchestration logic with error handling), groomer-lock.ts (DB-backed concurrency lock), and resolve-actor.ts (audit attribution) lack test coverage. These are risk areas where a regression would cause data integrity issues.

Evidence

• src/lib/automation-sync.ts — 382 lines, no test file
• src/lib/groomer/groomer-lock.ts — DB transaction with concurrent lock acquisition, no test
• src/lib/resolve-actor.ts — audit trail attribution, no test

Acceptance

Add unit tests covering the main execution paths and error conditions for these three modules.

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Decomposed from #648 (Weekly tech debt audit: misospace/dispatch - 2026-07-22).