fix: resolve all 28 findings from the 2026-06-12 full audit (TDD-pinned)

Critical (data integrity):
- warehouse inventory confirm: throw (not return) inside $transaction so a
  failed deficit line rolls back the surplus corrective receipt — retries
  no longer accumulate phantom stock
- warehouse issue confirm: validate batches against the COMBINED quantity
  of all lines (duplicate FIFO-resolved lines drove batches negative)
- attendance delete: restore vacation_used/sick_used for the deleted day
  (in-transaction, clamped at 0)

High:
- auth refresh: terminated sessions (replaced_at only) get a plain 401 —
  the theft branch (family revocation) now fires only on replaced_by_hash
- POST /users strips role_id for non-admin callers (mirrors PUT guard)
- issued-order transition flushes unsaved edits via the full save payload
  when dirty; server contract (items+status in one PUT) pinned
- received-invoices list: usePaginatedQuery + pager (rows 26+ unreachable)
- received-invoice dates: nullableIsoDateString + NaN guard before NAS save
  (Czech-format dates corrupted month/year, orphaned NAS files)
- leave approval skips Czech public holidays and books each calendar year's
  hours against its own balance (mirrors createLeave)

Medium/Low (classes):
- 52 Zod caps aligned to DB column widths across 7 schemas (over-cap input
  500ed at Prisma instead of a Czech 400)
- FK pre-validation: projects update + warehouse receipts/issues return
  Czech 400s instead of P2003 500s
- invoice PDF degrades gracefully when the CNB rate is unavailable
  (recap omitted instead of 500 + lost NAS archival)
- date boundaries: local-day filters (warehouse lists/reports, audit-log),
  @db.Date coercion on invoice dates
- plan updateEntry re-checks the per-cell cap (self-excluding)
- {id} tiebreaks on customers/received-invoices/warehouse-items sorts;
  /items honors the client sort param
- htmlToPdf relaunches once when the shared browser died mid-render
- offer number release parses the year from the document number (cross-year
  finalize+delete left permanent sequence gaps)
- trips/vehicles km fields integer-coerced; AI budget regated to
  settings.company|settings.system; Settings System tab no longer clobbers
  Firma numbering patterns; draft invoices hide the dead PDF button;
  dashboard quick-trip invalidates ["vehicles"]; TOTP secret cap 64;
  audit-log + invoice month buckets day-shift fixes

Docs: corrected the stale "Chromium has no CSS margin-box footers" claim
(html-to-pdf.ts + CLAUDE.md — margin boxes render since Chrome 131); audit
report M3 withdrawn accordingly.

~65 new pinning tests; every finding reproduced RED against the real test
DB before its fix. Suite: 58 files / 634 tests green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/services/projects.service.ts

@@ -108,6 +108,38 @@ export async function updateProject(id: number, body: Record<string, any>) {
     return { error: "Číslo projektu nelze změnit", status: 400 };
   }
 
+  // FK pre-validation (mirrors createProject): a dangling id would raise
+  // P2003 at Prisma and surface as a generic 500 — return the same Czech
+  // 400s as the create path. null still clears the FK.
+  if (body.customer_id != null) {
+    const customer = await prisma.customers.findUnique({
+      where: { id: Number(body.customer_id) },
+      select: { id: true },
+    });
+    if (!customer) return { error: "Zákazník nenalezen", status: 400 };
+  }
+  if (body.responsible_user_id != null) {
+    const user = await prisma.users.findUnique({
+      where: { id: Number(body.responsible_user_id) },
+      select: { id: true },
+    });
+    if (!user) return { error: "Zodpovědná osoba nenalezena", status: 400 };
+  }
+  if (body.quotation_id != null) {
+    const quotation = await prisma.quotations.findUnique({
+      where: { id: Number(body.quotation_id) },
+      select: { id: true },
+    });
+    if (!quotation) return { error: "Nabídka nenalezena", status: 400 };
+  }
+  if (body.order_id != null) {
+    const order = await prisma.orders.findUnique({
+      where: { id: Number(body.order_id) },
+      select: { id: true },
+    });
+    if (!order) return { error: "Zakázka nenalezena", status: 400 };
+  }
+
   const data: Record<string, unknown> = { modified_at: new Date() };
   const strFields = ["name", "status", "notes"];
   for (const f of strFields)