perf(registratura): lightweight API mode strips base64 attachments from list

ROOT CAUSE: RegistryEntry stores file attachments as base64 strings in JSON.
A single 5MB PDF becomes ~6.7MB of base64. With 6 entries, the exportAll()
endpoint was sending 30-60MB of JSON on every page load  taking 2+ minutes.

Fix: Added ?lightweight=true parameter to /api/storage GET endpoint.
When enabled, stripHeavyFields() recursively removes large 'data' and
'fileData' string fields (>1KB) from JSON values, replacing with '__stripped__'.

Changes:
- /api/storage route.ts: stripHeavyFields() + lightweight query param
- StorageService.export(): accepts { lightweight?: boolean } option
- DatabaseStorageAdapter.export(): passes lightweight flag to API
- LocalStorageAdapter.export(): accepts option (no-op, localStorage is fast)
- useStorage.exportAll(): passes options through
- registry-service.ts: getAllEntries() uses lightweight=true by default
- registry-service.ts: new getFullEntry() loads single entry with full data
- use-registry.ts: exports loadFullEntry() for on-demand full loading
- registratura-module.tsx: handleEdit/handleNavigateEntry load full entry

Result: List loading transfers ~100KB instead of 30-60MB. Editing loads
full data for a single entry on demand (~5-10MB for one entry vs all).

src/modules/registratura/hooks/use-registry.ts

@@ -13,6 +13,7 @@ import type {
 } from "../types";
 import {
   getAllEntries,
+  getFullEntry,
   saveEntry,
   deleteEntry,
   generateRegistryNumber,
@@ -255,6 +256,17 @@ export function useRegistry() {
     return true;
   });
 
+  /**
+   * Load a single entry WITH full attachment data (for editing).
+   * The list uses lightweight mode that strips base64 data.
+   */
+  const loadFullEntry = useCallback(
+    async (id: string): Promise<RegistryEntry | null> => {
+      return getFullEntry(storage, id);
+    },
+    [storage],
+  );
+
   return {
     entries: filteredEntries,
     allEntries: entries,
@@ -265,6 +277,7 @@ export function useRegistry() {
     updateEntry,
     removeEntry,
     closeEntry,
+    loadFullEntry,
     addDeadline,
     resolveDeadline,
     removeDeadline,