docs(fly): add private/hardened deployment guide

- Add fly.private.toml template for deployments with no public IP
- Add "Private Deployment (Hardened)" section to Fly docs
- Document how to convert existing deployment to private-only
- Add security notes recommending env vars over config file for secrets

This addresses security concerns about Clawdbot gateways being
discoverable on internet scanners (Shodan, Censys). Private deployments
are accessible only via fly proxy, WireGuard, or SSH.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/platforms/fly.md

@@ -39,7 +39,9 @@ fly volumes create clawdbot_data --size 1 --region iad
 
 ## 2) Configure fly.toml
 
-Edit `fly.toml` to match your app name and requirements:
+Edit `fly.toml` to match your app name and requirements.
+
+**Security note:** The default config exposes a public URL. For a hardened deployment with no public IP, see [Private Deployment](#private-deployment-hardened) or use `fly.private.toml`.
 
 ```toml
 app = "my-clawdbot"  # Your app name
@@ -104,6 +106,7 @@ fly secrets set DISCORD_BOT_TOKEN=MTQ...
 **Notes:**
 - Non-loopback binds (`--bind lan`) require `CLAWDBOT_GATEWAY_TOKEN` for security.
 - Treat these tokens like passwords.
+- **Prefer env vars over config file** for all API keys and tokens. This keeps secrets out of `clawdbot.json` where they could be accidentally exposed or logged.
 
 ## 4) Deploy
 
@@ -337,6 +340,110 @@ fly machine update <machine-id> --vm-memory 2048 --command "node dist/index.js g
 
 **Note:** After `fly deploy`, the machine command may reset to what's in `fly.toml`. If you made manual changes, re-apply them after deploy.
 
+## Private Deployment (Hardened)
+
+By default, Fly allocates public IPs, making your gateway accessible at `https://your-app.fly.dev`. This is convenient but means your deployment is discoverable by internet scanners (Shodan, Censys, etc.).
+
+For a hardened deployment with **no public exposure**, use the private template.
+
+### When to use private deployment
+
+- You only make **outbound** calls/messages (no inbound webhooks)
+- You use **ngrok or Tailscale** tunnels for any webhook callbacks
+- You access the gateway via **SSH, proxy, or WireGuard** instead of browser
+- You want the deployment **hidden from internet scanners**
+
+### Setup
+
+Use `fly.private.toml` instead of the standard config:
+
+```bash
+# Deploy with private config
+fly deploy -c fly.private.toml
+```
+
+Or convert an existing deployment:
+
+```bash
+# List current IPs
+fly ips list -a my-clawdbot
+
+# Release public IPs
+fly ips release <public-ipv4> -a my-clawdbot
+fly ips release <public-ipv6> -a my-clawdbot
+
+# Allocate private-only IPv6
+fly ips allocate-v6 --private -a my-clawdbot
+```
+
+After this, `fly ips list` should show only a `private` type IP:
+```
+VERSION  IP                   TYPE             REGION
+v6       fdaa:x:x:x:x::x      private          global
+```
+
+### Accessing a private deployment
+
+Since there's no public URL, use one of these methods:
+
+**Option 1: Local proxy (simplest)**
+```bash
+# Forward local port 3000 to the app
+fly proxy 3000:3000 -a my-clawdbot
+
+# Then open http://localhost:3000 in browser
+```
+
+**Option 2: WireGuard VPN**
+```bash
+# Create WireGuard config (one-time)
+fly wireguard create
+
+# Import to WireGuard client, then access via internal IPv6
+# Example: http://[fdaa:x:x:x:x::x]:3000
+```
+
+**Option 3: SSH only**
+```bash
+fly ssh console -a my-clawdbot
+```
+
+### Webhooks with private deployment
+
+If you need webhook callbacks (Twilio, Telnyx, etc.) without public exposure:
+
+1. **ngrok tunnel** - Run ngrok inside the container or as a sidecar
+2. **Tailscale Funnel** - Expose specific paths via Tailscale
+3. **Outbound-only** - Some providers (Twilio) work fine for outbound calls without webhooks
+
+Example voice-call config with ngrok:
+```json
+{
+  "plugins": {
+    "entries": {
+      "voice-call": {
+        "enabled": true,
+        "config": {
+          "provider": "twilio",
+          "tunnel": { "provider": "ngrok" }
+        }
+      }
+    }
+  }
+}
+```
+
+The ngrok tunnel runs inside the container and provides a public webhook URL without exposing the Fly app itself.
+
+### Security benefits
+
+| Aspect | Public | Private |
+|--------|--------|---------|
+| Internet scanners | Discoverable | Hidden |
+| Direct attacks | Possible | Blocked |
+| Control UI access | Browser | Proxy/VPN |
+| Webhook delivery | Direct | Via tunnel |
+
 ## Notes
 
 - Fly.io uses **x86 architecture** (not ARM)