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/package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.1.0",
       "dependencies": {
         "axios": "^1.6.7",
+        "dexie": "^4.2.1",
         "pinia": "^2.1.7",
         "vis-data": "^7.1.9",
         "vis-network": "^9.1.9",
@@ -812,6 +813,12 @@
         "node": ">=0.4.0"
       }
     },
+    "node_modules/dexie": {
+      "version": "4.4.3",
+      "resolved": "https://registry.npmjs.org/dexie/-/dexie-4.4.3.tgz",
+      "integrity": "sha512-N+3IGQ3HPlyO2YAkntGAwitm42BpBGV86MttzUMiRzWLa4NGh0pltVRcUVF4ybL/OnXjCrr9k7SDPIKkFYP2Lg==",
+      "license": "Apache-2.0"
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "license": "MIT",