Add local-first SPA architecture and containerized production deploy.

Move data access to use-cases and IndexedDB repositories with optional
remote fallback, changelog/sync ports, and encrypted local backup.
Add production Docker Compose (nginx frontend + optional backend) and
Apache host proxy configuration for deployment.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/application/usecases/contacts.js

@@ -0,0 +1,44 @@
+import { appendChange } from '../../infrastructure/sync/changeLogRepository'
+import { getContactRepository } from '../../infrastructure/repositories/repositoryFactory'
+
+const contactRepo = () => getContactRepository()
+
+export async function listContacts(search = '') {
+  return contactRepo().list(search)
+}
+
+export async function getContactById(id) {
+  return contactRepo().getById(id)
+}
+
+export async function createContact(payload) {
+  const created = await contactRepo().create(payload)
+  await appendChange({
+    entityType: 'contact',
+    entityId: created.id,
+    op: 'created',
+    payloadPatch: created,
+  })
+  return created
+}
+
+export async function updateContact(id, payload) {
+  const updated = await contactRepo().update(id, payload)
+  await appendChange({
+    entityType: 'contact',
+    entityId: id,
+    op: 'updated',
+    payloadPatch: payload,
+  })
+  return updated
+}
+
+export async function deleteContact(id) {
+  await contactRepo().remove(id)
+  await appendChange({
+    entityType: 'contact',
+    entityId: id,
+    op: 'deleted',
+    payloadPatch: {},
+  })
+}