feat(discipline): place the lever-rerun, lever-audit, shared-recipe and baseline-first principle parts #12145

Parent #7589 decides that pstack's principles are placed "as reasoned sentences in the phase-skill step that applies them, fallback when discipline is off; no standalone principle skills, no principles plugin" (D58, Q174, Q175). The owner approved this 2026-10-15 (poteto-review decision rows 58 and 105). The wording rule the owner accepted (Q175) is that each placed part:

• states the reason and the test that shows it applies (for example "a guard is a fix only when the state it handles is legitimate"), rather than a bare rule;
• names the standard file or discipline it comes from;
• where it sends work to a /discipline:* skill, carries a fallback for when that skill is unavailable, in the form plugins/implementation/skills/implement/SKILL.md:110 uses.

This slice places four parts from Lauren Tan's build-the-lever and sequence-verifiable-units principles, none of which is on main:

• 3c: a lever is safe to rerun when a second run on the pilot leaves no diff;
• 3g: citing a lever with no script in the diff means it was not applied;
• 3f: fanned-out workers read one shared recipe kept outside their write scope;
• 21f: baseline capture comes before the treatment, and scaffold before feature, in the delivery order.

Done when

• plugins/discipline/skills/script-the-deterministic-work/SKILL.md lever-check step 4 says to run the lever a second time on the pilot and expect no diff, with the reason (a lever that changes its own output on a rerun cannot be rerun safely across the remaining sites).
• The same skill's audit list gains an item: work that cites a lever but has no script in its diff did not apply one, with the test that shows it.
• plugins/implementation/skills/implement-dispatch/SKILL.md, in the brief-composing step, says that when several workers apply one recipe, the recipe lives in one file outside every worker's write scope and each brief points at it, with the reason (a copy per brief drifts, and a worker editing it changes the others' recipe).
• plugins/implementation/skills/implement/SKILL.md's delivery-order rule names two more orders, each with its reason: a baseline is captured before the change it measures, and a scaffold lands before the feature built on it.
• Each added sentence follows the wording rule above. Any sentence that sends work to a /discipline:* skill carries the fallback.
• .changes/discipline/*.md and .changes/implementation/*.md fragments with bump: patch describe the additions.
• The PR's CI is green.

Out of scope

• Gated parts 3h (commit the lever when the work outlives the session), 1c and 19d: they land only with stumble or eval evidence.
• A principles plugin or principle skills.

Parent: #7589