feat: add update instructions dialog, email notifications, and capture date sorting

- Add Update Instructions Dialog with environment-specific commands (Docker/Git/Standalone)
- Add email notification settings for new version alerts
- Add "Sort by Capture Date" option using EXIF metadata extraction
- Fix E2E tests by loading environment variables via dotenv
- Add test-images/ and backend/*.db to .gitignore

Closes #181

backend/package-lock.json

@@ -20,6 +20,7 @@
         "cookie-parser": "^1.4.7",
         "cors": "^2.8.5",
         "dotenv": "^16.0.3",
+        "exifr": "^7.1.3",
         "express": "^4.18.2",
         "express-rate-limit": "^6.7.0",
         "express-validator": "^7.0.1",
@@ -5730,6 +5731,12 @@
       "dev": true,
       "license": "ISC"
     },
+    "node_modules/exifr": {
+      "version": "7.1.3",
+      "resolved": "https://registry.npmjs.org/exifr/-/exifr-7.1.3.tgz",
+      "integrity": "sha512-g/aje2noHivrRSLbAUtBPWFbxKdKhgj/xr1vATDdUXPOFYJlQ62Ft0oy+72V6XLIpDJfHs6gXLbBLAolqOXYRw==",
+      "license": "MIT"
+    },
     "node_modules/exit": {
       "version": "0.1.2",
       "resolved": "https://registry.npmjs.org/exit/-/exit-0.1.2.tgz",