feat: add sign-in flow, routing shell, and searchable book list

Pin @testing-library/jest-dom to ~6.9.1 (6.10.0 is npm-deprecated).

Claude-Session: https://claude.ai/code/session_01M9MLit5Ko3X4s7rzC5Kv7X

package-lock.json

@@ -15,7 +15,7 @@
       "devDependencies": {
         "@tailwindcss/vite": "^4.3.3",
         "@testing-library/dom": "^10.4.2",
-        "@testing-library/jest-dom": "^6.10.0",
+        "@testing-library/jest-dom": "~6.9.1",
         "@testing-library/react": "^16.3.3",
         "@testing-library/user-event": "^14.6.7",
         "@types/node": "^24.10.1",
@@ -1768,10 +1768,9 @@
       }
     },
     "node_modules/@testing-library/jest-dom": {
-      "version": "6.10.0",
-      "resolved": "https://registry.npmjs.org/@testing-library/jest-dom/-/jest-dom-6.10.0.tgz",
-      "integrity": "sha512-HQwu0KaB2zyT0iLzBL+8CLyZDL3KlZlZJ+2iyc9uCUnlJVskJU/UlPuVCyIPhtukjPQdT2QNoR5nCP5FqTmmDQ==",
-      "deprecated": "Incorrect minor release with breaking changes (Node >=22 and required @testing-library/dom peer). Use 6.9.1 for the 6.x line, or upgrade to 7.0.0.",
+      "version": "6.9.1",
+      "resolved": "https://registry.npmjs.org/@testing-library/jest-dom/-/jest-dom-6.9.1.tgz",
+      "integrity": "sha512-zIcONa+hVtVSSep9UT3jZ5rizo2BsxgyDYU7WFD5eICBE7no3881HGeb/QkGfsJs6JTkY1aQhT7rIPC7e+0nnA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
@@ -1783,12 +1782,9 @@
         "redent": "^3.0.0"
       },
       "engines": {
-        "node": ">=22",
+        "node": ">=14",
         "npm": ">=6",
         "yarn": ">=1"
-      },
-      "peerDependencies": {
-        "@testing-library/dom": ">=10 <11"
       }
     },
     "node_modules/@testing-library/jest-dom/node_modules/dom-accessibility-api": {