Switch auth to plain-text password env var (remove bcrypt)

- Replace ADMIN_PASSWORD_HASH with ADMIN_PASSWORD in auth route and docker-compose
- Remove bcryptjs / @types/bcryptjs dependencies
- Delete scripts/hashPassword.ts (no longer needed)

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

package.json

@@ -19,7 +19,6 @@
   },
   "dependencies": {
     "@prisma/client": "^5.22.0",
-    "bcryptjs": "^2.4.3",
     "better-sqlite3": "^11.5.0",
     "cookie-parser": "^1.4.7",
     "cors": "^2.8.5",
@@ -28,7 +27,6 @@
     "jsonwebtoken": "^9.0.2"
   },
   "devDependencies": {
-    "@types/bcryptjs": "^2.4.6",
     "@types/better-sqlite3": "^7.6.12",
     "@types/cookie-parser": "^1.4.8",
     "@types/cors": "^2.8.17",