feat(record): conflict diff modal на 409 save (handoff line 444)

Когда PUT /records/{key} возвращает 409 (optimistic-lock fail — другой
пользователь сохранил тот же record между нашим load и submit'ом),
открываем ConflictDiffModal.

Component:
- Header: 'Конфликт сохранения · {DICT}' + business key
- Diff body: refetch server state via useRecordRaw, иди по union ключей
  local + server, оставь только отличающиеся. Per-row: field name (mono)
  + ваше значение (accent-bg) + серверное (surface-2)
- Footer 3 actions:
  - Отмена: close, оставить editor open
  - Загрузить серверное: discard local, refetch records, close editor
  - Перезаписать: re-submit current payload (если опять 409 → новый diff)
- Backend-friendly: не требует server diff endpoint, client считает diff
  client-side через JSON.stringify equality

Route wiring:
- onError handler distinguishes generic 409 (open diff modal) от
  специальных кодов: x_references_blocked_by_dependents,
  x_references_cascade_required, draft_required — те идут в свои dialogs
- Conflict state ({payload, businessKey}) capture'ит local data чтобы
  показать в diff даже после reset формы

ordinis-admin-ui/src/routes/dictionaries.$name.tsx

@@ -39,6 +39,7 @@ import { DictionaryHubView } from '@/components/lineage/DictionaryHubView'
 import { CascadeConfirmDialog } from '@/components/lineage/CascadeConfirmDialog'
 import { RecordHistoryDrawer } from '@/components/record/RecordHistoryDrawer'
 import { RecordDrawer } from '@/components/record/RecordDrawer'
+import { ConflictDiffModal } from '@/components/record/ConflictDiffModal'
 import { WorkflowBanner } from '@/components/editor/WorkflowBanner'
 import { EditorInfoPanel } from '@/components/editor/EditorInfoPanel'
 import { ExportModal } from '@/components/editor/ExportModal'
@@ -189,6 +190,12 @@ function DictionaryDetail() {
   const [aoiOpen, setAoiOpen] = useState(false)
   const [timeTravelOpen, setTimeTravelOpen] = useState(false)
   const [exportOpen, setExportOpen] = useState(false)
+  /** 409 save conflict: capture local payload + businessKey для diff modal.
+   *  Открывается из createMut/updateMut onError когда status===409. */
+  const [conflict, setConflict] = useState<{
+    payload: CreateRecordRequest
+    businessKey: string
+  } | null>(null)
   /** Phase 3 dict-relationships-v2: cascade dialog state. Открывается из 409
    *  на close, или явным action из record menu. */
   const [cascadeKey, setCascadeKey] = useState<string | undefined>(undefined)
@@ -474,6 +481,26 @@ function DictionaryDetail() {
       ...req,
       validFrom: req.validFrom && req.validFrom.length > 0 ? req.validFrom : nowIsoLocal(),
     }
+    // 409 conflict handler — handoff line 444. Detect optimistic-lock
+    // mismatch and open ConflictDiffModal (diff editor's payload vs server
+    // current state). Other 409 codes (cascade, draft_required) обрабатываются
+    // отдельно — здесь только generic conflict ("entity changed concurrently").
+    const handleSaveError = (err: unknown, bk: string) => {
+      const status = (err as { response?: { status?: number } })?.response?.status
+      const code = (err as { response?: { data?: { code?: string } } })
+        ?.response?.data?.code
+      if (status !== 409) return
+      // Specific 409 codes use their own dialogs — skip those.
+      if (
+        code === 'x_references_blocked_by_dependents' ||
+        code === 'x_references_cascade_required' ||
+        code === 'draft_required'
+      ) {
+        return
+      }
+      // Generic 409 = optimistic-lock conflict. Open diff modal.
+      setConflict({ payload: submitReq, businessKey: bk })
+    }
     if (edit.kind === 'create') {
       createMut.mutate(
         { payload: submitReq, idempotencyKey: recordIdempotencyKey },
@@ -482,6 +509,11 @@ function DictionaryDetail() {
             setEdit({ kind: 'closed' })
             resetRecordIdempotencyKey()
           },
+          onError: (err) => {
+            // Create rarely conflicts (no prior record to lock), но если backend
+            // вернёт 409 по уникальному ключу — businessKey возьмём из payload.
+            handleSaveError(err, submitReq.businessKey ?? '')
+          },
         },
       )
       return
@@ -498,6 +530,7 @@ function DictionaryDetail() {
             setEdit({ kind: 'closed' })
             resetRecordIdempotencyKey()
           },
+          onError: (err) => handleSaveError(err, edit.record.businessKey),
         },
       )
     }
@@ -1123,6 +1156,58 @@ function DictionaryDetail() {
         initial={aoi?.geojson ?? null}
       />
 
+      {/* Conflict diff modal — opens on 409 generic conflict (optimistic lock).
+        * Diff: editor payload vs server current state (refetched). Three actions:
+        *   - Отмена: close modal, keep editor (user retry/edit manually)
+        *   - Загрузить серверное: discard local, open editor с server snapshot
+        *   - Перезаписать: re-submit with current payload (will overwrite if no
+        *     new conflict — backend has no force-overwrite endpoint поэтому
+        *     просто retry; если опять 409 — modal снова откроется). */}
+      {conflict && (
+        <ConflictDiffModal
+          open
+          onClose={() => setConflict(null)}
+          localPayload={conflict.payload}
+          dictionaryName={name}
+          businessKey={conflict.businessKey}
+          onReloadServer={() => {
+            // Discard local edits, refetch records → пользователь увидит
+            // актуальное состояние. Закрываем editor; user может открыть
+            // запись ещё раз для редактирования с правильной базы.
+            setConflict(null)
+            setEdit({ kind: 'closed' })
+            resetRecordIdempotencyKey()
+            void recordsResult.refetch()
+          }}
+          onOverwrite={() => {
+            // Re-submit с current payload. Backend re-evaluates; если record
+            // изменился ещё раз → новый 409, modal откроется заново.
+            const payload = conflict.payload
+            const bk = conflict.businessKey
+            setConflict(null)
+            if (edit.kind === 'edit') {
+              updateMut.mutate(
+                { businessKey: bk, payload, idempotencyKey: recordIdempotencyKey },
+                {
+                  onSuccess: () => {
+                    setEdit({ kind: 'closed' })
+                    resetRecordIdempotencyKey()
+                  },
+                  onError: (err) => {
+                    const status = (err as { response?: { status?: number } })
+                      ?.response?.status
+                    if (status === 409) {
+                      // Re-open diff modal с свежим server state.
+                      setConflict({ payload, businessKey: bk })
+                    }
+                  },
+                },
+              )
+            }
+          }}
+        />
+      )}
+
       {/* Export modal — only mount when open. Same lazy pattern as Time-travel. */}
       {exportOpen && detailQuery.data && (
         <ExportModal