docs: add POLL_INTERVAL to README, .env.sample, and .env.example

- Document background polling and on-demand mode in README
- Add POLL_INTERVAL to all config examples (Docker, Compose, .env)
- New 'Background Polling' section in Features
- Sanitize leaked credentials in .env.example

.env.example

@@ -1,5 +1,10 @@
 # Server Configuration
 PORT=3001
+LOG_LEVEL=info
+
+# Background polling interval in ms (default: 5000)
+# Set to 0 or "off" to disable and fetch on-demand instead
+# POLL_INTERVAL=5000
 
 # Emby Configuration (single instance)
 EMBY_URL=http://localhost:8096
@@ -16,7 +21,4 @@ SONARR_INSTANCES=[{"name": "Primary", "url": "http://localhost:8989", "apiKey":
 RADARR_INSTANCES=[{"name": "Primary", "url": "http://localhost:7878", "apiKey": "your_api_key"}]
 
 # qBittorrent Instances (JSON array)
-QBITTORRENT_INSTANCES=[
-  {"name": "ransackedcrew", "url": "https://qbittorrent.ransackedcrew.info", "username": "gronod", "password": "K32D&JDjtHA&mC"},
-  {"name": "i3omb", "url": "https://qbittorrent.i3omb.com", "username": "admin", "password": "b053288369XX!"}
-]
+QBITTORRENT_INSTANCES=[{"name": "main", "url": "http://localhost:8080", "username": "admin", "password": "your_password"}]

.env.sample

@@ -14,6 +14,14 @@ PORT=3001
 # - silent: No logging
 LOG_LEVEL=info
 
+# Background polling interval in milliseconds (default: 5000)
+# sofarr polls all services in the background and caches results so
+# dashboard requests are near-instant.
+# Set to 0, "off", "false", or "disabled" to disable background polling.
+# When disabled, data is fetched on-demand when a user opens the dashboard
+# and cached for 30 seconds so other users benefit from the same fetch.
+# POLL_INTERVAL=5000
+
 # =============================================================================
 # EMBY (Authentication - Required)
 # =============================================================================
@@ -74,4 +82,5 @@ RADARR_INSTANCES=[{"name":"main","url":"https://radarr.example.com","apiKey":"yo
 # 3. URLs should include protocol (http:// or https://)
 # 4. For qBittorrent, ensure Web UI is enabled in settings
 # 5. User downloads are matched by tags in Sonarr/Radarr - tag your media!
+# 6. Background polling keeps data fresh; disable it for low-resource setups
 # =============================================================================

README.md

@@ -108,6 +108,7 @@ docker run -d \
   -e SABNZBD_INSTANCES='[{"name":"main","url":"http://sabnzbd:8080","apiKey":"your-key"}]' \
   -e QBITTORRENT_INSTANCES='[{"name":"main","url":"http://qbit:8080","username":"admin","password":"pass"}]' \
   -e LOG_LEVEL=info \
+  -e POLL_INTERVAL=5000 \
   docker.i3omb.com/sofarr:latest
 ```
 
@@ -130,6 +131,7 @@ services:
       - SABNZBD_INSTANCES=[{"name":"main","url":"http://sabnzbd:8080","apiKey":"your-key"}]
       - QBITTORRENT_INSTANCES=[{"name":"main","url":"http://qbit:8080","username":"admin","password":"pass"}]
       - LOG_LEVEL=info
+      - POLL_INTERVAL=5000
 ```
 
 > **Tip:** You can also use a combination — mount a `.env` file for base config, and override specific values with `-e` flags. Environment variables always take precedence.
@@ -181,6 +183,8 @@ Open `http://localhost:3001` in your browser
 ```bash
 PORT=3001                           # Server port
 LOG_LEVEL=info                      # Logging: debug, info, warn, error, silent
+POLL_INTERVAL=5000                  # Background polling interval in ms (default: 5000)
+                                    # Set to 0 or "off" to disable (on-demand mode)
 ```
 
 ### Service Instances (JSON Array Format)
@@ -231,6 +235,18 @@ To see your downloads, you need to tag your media in Sonarr/Radarr:
 
 ## Features in Detail
 
+### Background Polling
+
+sofarr polls all configured services in the background and caches the results. Dashboard requests read from cache, making them near-instant regardless of how many services you have.
+
+| Setting | Behaviour |
+|---------|----------|
+| `POLL_INTERVAL=5000` (default) | Background poller fetches every 5s. Dashboard reads from cache instantly. |
+| `POLL_INTERVAL=10000` | Poll every 10 seconds. |
+| `POLL_INTERVAL=0` / `off` / `disabled` | No background polling. Data fetched on-demand when a user opens the dashboard, then cached for 30 seconds. |
+
+**On-demand mode** is useful for low-resource setups. When one user's browser refreshes, the fetched data is cached and served to all other users until it expires. A user with a faster refresh rate effectively keeps the cache warm for everyone.
+
 ### Real-Time Updates
 - Auto-refresh every 5 seconds (configurable: 1s, 5s, 10s, or off)
 - In-place DOM updates for smooth UI (no flickering)