feat: replace Redis with DragonflyDB

- Replace Redis server with DragonflyDB v1.40.1 (Redis protocol compatible)
- Stop redis-server service, enable dragonfly service on 127.0.0.1:6379
- Configure dragonfly in /etc/dragonfly/dragonfly.conf (bind 127.0.0.1, maxmemory 2gb)
- Update .env: remove REDIS_URL reference

Improve database reliability:
- Fix catalog-tree.ts: remove CAST(page_id AS CHAR) to enable index usage (122 rows vs 78k full scan)
- Fix catalog-repair.ts: replace sql.raw() string interpolation with parameterized sql queries using quoteIdentifier()
- Improve redis retry resilience: change retryStrategy to not give up after 3 attempts, enabling automatic reconnect after server restart

Update documentation:
- Update README: replace Redis references with DragonflyDB, add DragonflyDB setup section, update performance features list, update architecture diagram
- biome and typecheck pass clean

README.md

@@ -13,7 +13,7 @@ Features a premium animated homepage (typewriter hero, floating orbs, scroll cou
 | Node.js         | >= 22          | Required by Next.js 16                   |
 | pnpm            | >= 10.33.4     | Package manager (npm/yarn not supported) |
 | MySQL / MariaDB | 8.0+ / 10.6+   | Shared with the emulator                 |
-| Redis           | 7.x+           | Optional — caching, rate limiting, SSE   |
+| DragonflyDB     | 1.x+           | Optional — caching, rate limiting, SSE (Redis-protocol compatible) |
 | Java            | 17+            | Required only if building the emulator   |
 | Maven           | 3.9+           | Required only if building the emulator   |
 
@@ -56,7 +56,7 @@ HOTEL_NAME=YourHotel
 APP_URL=http://localhost:3000
 ```
 
-See `.env.example` for all optional variables (RCON, email, Redis, OAuth, PayPal, etc.).
+See `.env.example` for all optional variables (RCON, email, DragonflyDB, OAuth, PayPal, etc.).
 
 ### 4. ORM Setup & Type Generation
 
@@ -121,6 +121,60 @@ Open `http://localhost:3000` in your browser.
 
 ---
 
+## DragonflyDB (caching, rate limiting, SSE)
+
+DragonflyDB is a drop-in, Redis-compatible in-memory datastore. The CMS connects to it
+via `REDIS_URL` using the `ioredis` client, so no application code changes are needed —
+every Redis command (`PING`, `GET`, `SETEX`, `DEL`, `INCR`, `PEXPIRE`, `PTTL`) works
+unchanged. It is optional: without it the CMS falls back to in-process memory.
+
+### Install (Ubuntu/Debian)
+
+```bash
+curl -fsSL -o /tmp/dragonfly_amd64.deb \
+  https://github.com/dragonflydb/dragonfly/releases/download/v1.40.1/dragonfly_amd64.deb
+apt-get install -y /tmp/dragonfly_amd64.deb
+systemctl enable --now dragonfly
+```
+
+This installs a `dragonfly` systemd service and a config file at `/etc/dragonfly/dragonfly.conf`.
+
+### Configure
+
+```ini
+--bind=127.0.0.1
+--port=6379
+--maxmemory=2gb
+--version_check=false
+```
+
+- `--bind=127.0.0.1` keeps it private on the machine (matches `REDIS_URL=redis://127.0.0.1:6379`).
+- `--port=6379` is the default Redis port, so `.env` stays unchanged.
+- `--maxmemory` must be at least `0.25GiB` per CPU thread (e.g. `2gb` on a 6-thread server).
+- `--version_check=false` disables the periodic outbound update check.
+- Snapshots are written to `--dir` (`/var/lib/dragonfly/dump-*.dfs`).
+
+### Point the CMS at it
+
+```dotenv
+REDIS_URL=redis://127.0.0.1:6379?connect_timeout=2
+```
+
+### Useful commands
+
+```bash
+redis-cli PING                 # → PONG
+redis-cli FLUSHALL             # clear the cache
+systemctl status dragonfly     # service health
+```
+
+Verify everything is wired up via the health endpoint:
+`/api/health` should report `"redis": true`. The ioredis client automatically reconnects
+after a DragonflyDB restart.
+
+> **Note:** if an old Redis install still occupies port 6379, stop it first:
+> `systemctl disable --now redis-server`.
+
 ## Nginx Configuration
 
 The CMS is designed to run behind an nginx reverse proxy. Below is a reference configuration covering SSL termination, WebSocket upgrade, proxy caching, and the Habbo imager integration.
@@ -402,7 +456,7 @@ The CMS runs behind an nginx reverse proxy on the default port 3000. Static asse
 | **View Transitions API**       | Native browser transitions between page navigations            |
 | **Lenis Smooth Scroll**        | Fluid, customizable scrolling (respects `prefers-reduced-motion`) |
 | **Server-Sent Events**         | Real-time radio now-playing & listeners via SSE (no polling)   |
-| **Redis Caching**              | Caches API responses (home, radio config) up to 30s in Redis   |
+| **DragonflyDB Caching**       | Caches API responses (home, radio config) up to 30s in DragonflyDB |
 | **Bundle Analyzer**            | Run `pnpm analyze` to visualize and optimize bundle sizes      |
 | **RCON (TCP Socket)**          | Live commands to the emulator (credits, badges, kick, ban)     |
 | **Streaming & Suspense**       | Next.js App Router streaming for fast page loads               |
@@ -437,9 +491,9 @@ The CMS runs behind an nginx reverse proxy on the default port 3000. Static asse
 │   │   ├── auth/              # NextAuth, password hashing, 2FA, SSO tickets
 │   │   ├── services/          # RCON, email, currency, PayPal, alerts
 │   │   ├── db.ts              # Drizzle connection singleton (runtime)
-│   │   ├── cached-db.ts       # Redis-backed query cache helpers
-│   │   ├── redis.ts           # Redis client (ioredis)
-│   │   ├── redis-cache.ts     # Redis caching utility for API routes
+│   │   ├── cached-db.ts       # DragonflyDB-backed query cache helpers
+│   │   ├── redis.ts           # Cache client (ioredis → DragonflyDB)
+│   │   ├── redis-cache.ts     # Caching utility for API routes (uses DragonflyDB)
 │   │   ├── cache.ts           # In-memory cache fallback
 │   │   ├── motion.ts          # Framer Motion animation variants
 │   │   └── use-event-source.ts # React hook for SSE subscriptions