feat: add 4 built-in gradients, searchable gradient picker, cleaner modal titles

- Add warm, cool, neon, pastel built-in gradients (promoted from frontend presets)
- Change gradient seeding to add missing built-ins on every startup (not just first run)
- Add searchable option to IconSelect component for filtering by name
- Enable search on gradient, effect palette, and audio palette pickers
- Simplify modal titles: "Add Gradient" / "Edit Gradient" instead of "Add Color Strip Source: Gradient"
- Update INSTALLATION.md and .env.example

INSTALLATION.md

@@ -121,9 +121,9 @@ Screen capture from inside a container requires X11 access. Uncomment `network_m
    Optional extras:
 
    ```bash
-   pip install ".[camera]"          # Webcam capture via OpenCV
    pip install ".[perf]"            # DXCam, BetterCam, WGC (Windows only)
    pip install ".[notifications]"   # OS notification capture
+   pip install ".[tray]"            # System tray icon (Windows only)
    pip install ".[dev]"             # pytest, black, ruff (development)
    ```
 
@@ -155,13 +155,13 @@ Option A -- edit the config file:
 # server/config/default_config.yaml
 auth:
   api_keys:
-    main: "your-secure-key-here"   # replace the dev key
+    dev: "your-secure-key-here"   # replace the dev key
 ```
 
 Option B -- set an environment variable:
 
 ```bash
-export WLED_AUTH__API_KEYS__main="your-secure-key-here"
+export WLED_AUTH__API_KEYS__dev="your-secure-key-here"
 ```
 
 Generate a random key:
@@ -257,6 +257,7 @@ See [`server/.env.example`](server/.env.example) for every available variable wi
 | `WLED_SERVER__LOG_LEVEL` | `INFO` | `DEBUG`, `INFO`, `WARNING`, `ERROR` |
 | `WLED_SERVER__CORS_ORIGINS` | `["http://localhost:8080"]` | Allowed CORS origins (JSON array) |
 | `WLED_AUTH__API_KEYS` | `{"dev":"development-key..."}` | API keys (JSON object) |
+| `WLED_STORAGE__DATABASE_FILE` | `data/ledgrab.db` | SQLite database path |
 | `WLED_MQTT__ENABLED` | `false` | Enable MQTT for HA auto-discovery |
 | `WLED_MQTT__BROKER_HOST` | `localhost` | MQTT broker address |
 | `WLED_DEMO` | `false` | Enable demo mode (sandbox with virtual devices) |