fix: 拦截已删除报销进入付款创建（09-04-reimbursement-state-gap-finance-view）

.trellis/spec/hyb-oa/backend-fastify-prisma.md

@@ -103,6 +103,17 @@ Wrong: treat a notice count or pending-batch aggregate as the complete finance w
 - Creation takes source locks, reloads facts, runs the resolver and only then
   allocates/creates a batch, items, success audit and notifications. Blocked
   preflight/create must not emit any of those success side effects.
+- New-payment candidates and `loadEntitySnapshots` both require
+  `deleted_at: null`; an approved status alone is not the deletion guard.
+  A deleted source yields `payment_batch.source_not_found` in readiness and
+  HTTP 404 on creation, including when marked between preflight and source lock.
+  Keep deletion-filter awareness in query test doubles and exercise this
+  defensive fixture even though current deletion only permits draft/rejected.
+- Do not mechanically apply creation filters to historical batch detail,
+  frozen snapshots or legacy evidence reads. Preserve their existing authority
+  checks and test that retained history remains readable. This does not permit
+  deleting approved/reserved sources; any such future change must also review
+  existing-batch export, review and execution paths, not just creation.
 - Public blockers contain only reason code and optional source association.
   Neither decrypted account numbers nor account snapshots enter readiness DTOs.
   Bank-channel constraints must not silently become constraints on cash or other