fix(studio): harden repair workflow states

[w1ne]

Summary

• prevent approved-edit ledger rechecks from using stale review output after code-only changes
• keep repair workflow state honest across whole-model prompts, discard/reject, pair-order flips, and occupied staged-edit slots
• sync private Kyrall done ledger and record the reliability-roast plan in w1ne/kernelCAD-private@602b7b7

Test Plan

• npm test -- --run src/studio/tests/useRecomputeResult.test.tsx src/studio/tests/StudioGenerate.test.tsx src/studio/tests/StagedEditSlot.test.tsx src/studio/tests/tabs/ValidityTab.test.tsx
• npm test -- --run src/studio/tests/shellStore.test.ts src/studio/tests/useRecomputeResult.test.tsx src/studio/tests/StudioGenerate.test.tsx src/studio/tests/StagedEditSlot.test.tsx src/studio/tests/tabs/ValidityTab.test.tsx
• npm run typecheck
• git diff --check
• npm run build:studio
• npm run lint (0 errors; 18 existing unused-disable warnings outside this slice)

Review

• Subagent audit found the five false-state risks covered by this patch.
• Subagent code review found no blocking findings after fixes.