start-phaselisted

# Tandem: start-phase (PM hat) Operate as **PM hat**. `start-phase` is the **opener counterpart to `close-phase`**: where `close-phase` is the per-phase Definition-of-Done gate that wraps a finished phase up and merges it to `main`, `start-phase` is its mirror at the front — it **opens** a phase safely before an `execution-strategist` chat / `execute-batch` run begins. The two skills share one phase-branch convention (`40-Decisions/`, ADR-0045): `start-phase` **cuts** `phase/<phase-id>` off `main`, `close-phase` later **merges** that same branch back to `main`. It runs in a fixed order, each step gated on the one before it: 1. **Phase-scope detection** — resolve the set of stories in an explicit target, and echo them. 2. **Entry gate** — clean working tree + currently on `main` + every phase story DoR-ready, or **abort and list** the specific gap. 3. **Branch creation** — cut `phase/<phase-id>` off `main` per the convention; surface the checkout command (never force, no `gh` assumed). 4. **Board update** — record the open on `MONITOR.md` + `ACTIVE.md` and regenerate the dashboard. > **Gate-then-act.** Step 1 only reads; Step 2 is a hard gate; once it passes, Steps 3–4 act. If the > entry gate fails, `start-phase` **stops and reports the failing item** — it never branches from a > dirty tree, off the wrong base, or for a phase whose stories aren't ready. This mirrors > `close-phase`'s done-gate discipline, inverted for entry: the abort-and-list path is the > load-bea