[Thermo-Nuclear][Wave 3] Decompose skills/poteto-mode/scripts/orch/store.ts below 1,000 lines #648

Parent #645 (Program Epic). Detail report: docs/audit/thermo-nuclear-636/04_codebase_file_size_and_complexity_thresholds.md.

Problem

skills/poteto-mode/scripts/orch/store.ts has grown to 1,677 lines, severely breaching the thermo-nuclear 1,000-line ceiling. It bundles domain types/errors, PID lock acquisition and probes, GitHub and Origin CLI base-chain traversal and loop detection, and TSV store CRUD operations into a single monolith.

Scope

• Extract skills/poteto-mode/scripts/orch/types.ts (~260 lines) for domain interfaces, errors, and validator parsers.
• Extract skills/poteto-mode/scripts/orch/lock.ts (~120 lines) for PID lock acquisition, holderIsDead, and release logic.
• Extract skills/poteto-mode/scripts/orch/frontier.ts (~320 lines) for Forge CLI querying (gh/origin), loop detection, and linear chain validation.
• Keep store.ts strictly under 950 lines, focused solely on table CRUD operations and re-exporting modules for full backwards compatibility.
• Ensure all 101 tests in skills/poteto-mode/scripts pass cleanly (bun test).