Feat: Replace Load More with Previous/Next pagination in library

Page size changes from 50 to 24. Library now shows discrete page navigation
with a "Page N of M" indicator, total image count, and URL state (?page=N)
so pages are bookmarkable and the browser Back button works. Tag filter
resets to page 1. Out-of-range page params are clamped silently.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/package-lock.json

@@ -31,6 +31,7 @@
         "karma": "~6.4.0",
         "karma-chrome-launcher": "~3.2.0",
         "karma-coverage": "~2.2.0",
+        "karma-firefox-launcher": "^2.1.3",
         "karma-jasmine": "~5.1.0",
         "karma-jasmine-html-reporter": "~2.1.0",
         "prettier": "^3.2.0",
@@ -10829,6 +10830,62 @@
         "semver": "bin/semver.js"
       }
     },
+    "node_modules/karma-firefox-launcher": {
+      "version": "2.1.3",
+      "resolved": "https://registry.npmjs.org/karma-firefox-launcher/-/karma-firefox-launcher-2.1.3.tgz",
+      "integrity": "sha512-LMM2bseebLbYjODBOVt7TCPP9OI2vZIXCavIXhkO9m+10Uj5l7u/SKoeRmYx8FYHTVGZSpk6peX+3BMHC1WwNw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "is-wsl": "^2.2.0",
+        "which": "^3.0.0"
+      }
+    },
+    "node_modules/karma-firefox-launcher/node_modules/is-docker": {
+      "version": "2.2.1",
+      "resolved": "https://registry.npmjs.org/is-docker/-/is-docker-2.2.1.tgz",
+      "integrity": "sha512-F+i2BKsFrH66iaUFc0woD8sLy8getkwTwtOBjvs56Cx4CgJDeKQeqfz8wAYiSb8JOprWhHH5p77PbmYCvvUuXQ==",
+      "dev": true,
+      "license": "MIT",
+      "bin": {
+        "is-docker": "cli.js"
+      },
+      "engines": {
+        "node": ">=8"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
+    "node_modules/karma-firefox-launcher/node_modules/is-wsl": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/is-wsl/-/is-wsl-2.2.0.tgz",
+      "integrity": "sha512-fKzAra0rGJUUBwGBgNkHZuToZcn+TtXHpeCgmkMJMMYx1sQDYaCSyjJBSCa2nH1DGm7s3n1oBnohoVTBaN7Lww==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "is-docker": "^2.0.0"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/karma-firefox-launcher/node_modules/which": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/which/-/which-3.0.1.tgz",
+      "integrity": "sha512-XA1b62dzQzLfaEOSQFTCOd5KFf/1VSzZo7/7TUjnya6u0vGGKzU96UQBZTAThCb2j4/xjBAyii1OhRLJEivHvg==",
+      "dev": true,
+      "license": "ISC",
+      "dependencies": {
+        "isexe": "^2.0.0"
+      },
+      "bin": {
+        "node-which": "bin/which.js"
+      },
+      "engines": {
+        "node": "^14.17.0 || ^16.13.0 || >=18.0.0"
+      }
+    },
     "node_modules/karma-jasmine": {
       "version": "5.1.0",
       "resolved": "https://registry.npmjs.org/karma-jasmine/-/karma-jasmine-5.1.0.tgz",