feat(documents)!: unify offers and issued orders end to end

One coherent pass over the two sibling document models, driven by a 3-lens
1:1 scan (~60 divergences inventoried) + user decisions. Migration adds
issued_orders.locked_by/locked_at and the issued_order_sections table
(mirror of scope_sections; applied to dev + test DBs).

Issued orders gained (offers as reference implementation):
- rich-text SECTIONS with CZ/EN titles, rendered on their own PDF page in
  the PO template's red style (shared DocumentSectionSchema, one-transaction
  create/update incl. items - fixes a torn-write bug)
- edit LOCKING (lock/heartbeat/unlock routes, 423 + holder name, 30s TTL =
  3 missed 10s heartbeats; locked_by enrichment on detail)
- archived-PDF serving: GET /:id/file reads the NAS copy (new
  readIssuedByNumber sweep) with live-render fallback + re-archive; offers'
  /file got the same fallback (kills the 'ulozte nabidku' dead end)
- NAS cleanup on delete, in-tx po_number uniqueness (409), collision-advancing
  number previews (also invoice previews), PUT returns assigned po_number

Offers hardened (issued as reference):
- VALID_TRANSITIONS enforced (no more numberless 'ordered' offers; invalidate
  follows the table; order creation only from active offers) +
  valid_transitions on detail
- explicit 400 instead of silent edits outside draft/active (mirrored on
  issued: explicit 400 replaced silent drops)
- customer existence check + Number(null)->0 clear bug fixed; delete of a
  linked offer -> 409 instead of P2003 500; error-token convention; Zod caps
  DB-aligned (desc 500/unit 20/number 50/project_code 100, isoDateString
  dates, ints for positions); audit old/new values + koncept fallbacks;
  list id tiebreaks; stats include trimmed; NAS delete dedupe

Frontend unification (6 new shared modules):
- components/document/{DocumentItemsEditor,SectionsEditor,LockBanner}
- hooks/{useDocumentLock,useUnsavedChangesGuard,useDocumentPdf(+list variant)}
- OfferDetail 1940->1100 lines, IssuedOrderDetail 1400->980: headline-only
  document number (form field removed), one form layout/readonly convention,
  view-permission opens read-only everywhere (issued's editable-for-viewers
  hole closed), server-driven transition buttons, dirty guard + Enter submit
  on both, useApiMutation everywhere (new opt-in envelope mode), fixed
  infinite spinner on failed detail fetch, draft PDFs hidden (no number yet)
- lists: supplier filter + count line on issued, Mena column dropped + mono
  numbers on offers, shared hardened per-row PDF flow (spinner, double-click
  guard, 401 close, blob cleanup), proper Czech quotes, real CTA empty
  states, query-lib cleanups (["offers","customers"] key, typed list rows,
  shared CurrencyAmount, retry:false on details)
- pdf-shared.ts: one escapeHtml/cleanQuillHtml(strict)/formatNum(NBSP)/
  formatCurrency/formatDate for all four PDF routes; offer PDF keeps its
  monochrome look (fractional qty fix: 1.5 no longer prints as 2); issued
  PDF language now comes from the document column

+49 tests (suite 364 -> 413). Each stage passed an independent review; final
cross-stage integration review verified the FE<->BE contracts.

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

src/schemas/offers.schema.ts

@@ -1,52 +1,43 @@
 import { z } from "zod";
 import {
-  numberFromForm,
+  nonNegativeIntFromForm,
   nonNegativeNumberFromForm,
   positiveNumberFromForm,
   nullableIntIdFromForm,
   booleanFromForm,
+  isoDateString,
+  DocumentSectionSchema,
 } from "./common";
 
+// Limits are DB-aligned: description VarChar(500), unit VarChar(20);
+// item_description is Text with the app-level 8000 cap used elsewhere.
 const QuotationItemSchema = z.object({
-  description: z.string().max(8000).nullish(),
+  description: z.string().max(500).nullish(),
   item_description: z.string().max(8000).nullish(),
   quantity: positiveNumberFromForm.default(1),
-  unit: z.string().max(255).nullish(),
-  unit_price: numberFromForm.default(0),
+  unit: z.string().max(20).nullish(),
+  unit_price: nonNegativeNumberFromForm.default(0),
   is_included_in_total: booleanFromForm.optional().default(true),
-  position: nonNegativeNumberFromForm.optional(),
+  // Int column — a float position would 500 at Prisma.
+  position: nonNegativeIntFromForm.optional(),
 });
 
-const ScopeSectionSchema = z.object({
-  title: z.string().max(255).nullish(),
-  title_cz: z.string().max(255).nullish(),
-  content: z.string().max(8000).nullish(),
-  position: nonNegativeNumberFromForm.optional(),
-});
+// Shared with issued orders (scope_sections ≡ issued_order_sections).
+const ScopeSectionSchema = DocumentSectionSchema;
 
+// NOTE: no top-level `.default()`s here — `UpdateQuotationSchema` derives from
+// this schema via `.partial()`, and Zod 4 still applies a field default when
+// the key is absent, which would silently inject status/currency/language
+// resets into every update payload. Create-time defaults live in
+// `createOffer` (service) instead.
 export const CreateQuotationSchema = z.object({
-  quotation_number: z.string().max(255).nullish(),
-  project_code: z.string().max(255).nullish(),
+  // DB: quotations.quotation_number VarChar(50).
+  quotation_number: z.string().max(50).nullish(),
+  // DB column is VarChar(100) — a longer value would 500 at Prisma.
+  project_code: z.string().max(100).nullish(),
   customer_id: nullableIntIdFromForm.nullish(),
-  created_at: z.string().max(255).nullish(),
-  valid_until: z.string().max(255).nullish(),
-  currency: z.string().max(20).optional().default("CZK"),
-  language: z.string().max(20).optional().default("cs"),
-  status: z
-    .enum(["draft", "active", "ordered", "invalidated"])
-    .optional()
-    .default("draft"),
-  scope_title: z.string().max(255).nullish(),
-  scope_description: z.string().max(8000).nullish(),
-  items: z.array(QuotationItemSchema).optional(),
-  sections: z.array(ScopeSectionSchema).optional(),
-});
-
-export const UpdateQuotationSchema = z.object({
-  project_code: z.string().max(255).nullish(),
-  customer_id: nullableIntIdFromForm.optional(),
-  created_at: z.union([z.string().max(255), z.null()]).optional(),
-  valid_until: z.union([z.string().max(255), z.null()]).optional(),
+  created_at: isoDateString.nullish(),
+  valid_until: isoDateString.nullish(),
   currency: z.string().max(20).optional(),
   language: z.string().max(20).optional(),
   status: z.enum(["draft", "active", "ordered", "invalidated"]).optional(),
@@ -56,5 +47,12 @@ export const UpdateQuotationSchema = z.object({
   sections: z.array(ScopeSectionSchema).optional(),
 });
 
+// Update = partial create MINUS the number: quotation numbers are immutable
+// (assigned by the sequence on finalize), so the field is stripped before it
+// can ever reach the service.
+export const UpdateQuotationSchema = CreateQuotationSchema.partial().omit({
+  quotation_number: true,
+});
+
 export type CreateQuotationInput = z.infer<typeof CreateQuotationSchema>;
 export type UpdateQuotationInput = z.infer<typeof UpdateQuotationSchema>;