Stop the post-merge audit from parking tasks as `failed` when deterministic
merge verification already proved the merged tree. Adds `postMergeAuditMode`
project setting (`block` | `warn` | `off`, default `block`) and a
verified-tree short-circuit for rebase-strategy overlap-only findings.
- packages/engine/src/merger.ts: new `resolvePostMergeAuditAction` helper
+ audit call site gated on `postMergeAuditMode` and verification-cache
lookup. Rebase + overlap-only + verified-tree → pass through with a
short-circuit log entry instead of throwing SquashAuditError.
- packages/core/src/types.ts, settings-schema.ts, index.ts: new
`PostMergeAuditMode` type, `postMergeAuditMode` field on Settings,
default `block`, exports `normalizePostMergeAuditMode`.
- packages/engine/src/__tests__/post-merge-audit-action.test.ts: unit
tests for the decision helper.
- packages/dashboard/app/components/SettingsModal.tsx: settings UI row.
- .changeset: minor bump for @runfusion/fusion.
The FN-3936 silent-drop guard is preserved: duplicate-subject findings
still block in `block` mode and squash-strategy audits still block
(no equivalent deterministic guarantee).
Fusion-Task-Id: FN-4333
e787036b80