fix(daemon): drain UI channel in headless mode to prevent panic

On PinePhone (headless display), the UI update receiver was dropped
immediately, causing sends from diag.rs to fail with SendError and
panic. Spawn a task that drains the channel until shutdown.

Fixes #657

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

daemon/src/display/headless.rs

@@ -7,10 +7,18 @@ use crate::config;
 use crate::display::DisplayState;
 
 pub fn update_ui(
-    _task_tracker: &TaskTracker,
+    task_tracker: &TaskTracker,
     _config: &config::Config,
-    _shutdown_token: CancellationToken,
+    shutdown_token: CancellationToken,
-    _ui_update_rx: Receiver<DisplayState>,
+    mut ui_update_rx: Receiver<DisplayState>,
 ) {
     info!("Headless mode, not spawning UI.");
+    task_tracker.spawn(async move {
+        loop {
+            tokio::select! {
+                _ = shutdown_token.cancelled() => break,
+                _ = ui_update_rx.recv() => {}
+            }
+        }
+    });
 }

doc/configuration.md

@@ -61,12 +61,6 @@ On the first detection of a crash, a diagnostic snapshot is saved to `/data/rayh
 
 If recovery fails after 5 attempts, the status will change to **failed**. A reboot of the device will reset WiFi.
 
-You can also configure WiFi during installation:
-
-```sh
-./installer orbic --admin-password 'mypassword' --wifi-ssid 'MyNetwork' --wifi-password 'networkpass'
-```
-
 ## WebDAV Upload
 
 Rayhunter can automatically upload finished recordings to a WebDAV server. When a `[webdav]` section is present in `config.toml`, a background worker periodically scans the recording store and uploads any closed entry that is older than `min_age_secs`. Each eligible entry uploads two files: the raw `.qmdl` capture and its `.ndjson` analysis output. After a successful upload the entry is either marked as uploaded in the manifest (and skipped on subsequent polls), or deleted locally if `delete_on_upload = true`. With no `[webdav]` section, no upload worker runs.

installer/src/tplink.rs

@@ -346,9 +346,13 @@ async fn tplink_launch_telnet_v5(admin_ip: &str) -> Result<(), Error> {
             admin_ip: admin_ip.to_owned(),
         });
 
-    let listener = tokio::net::TcpListener::bind("127.0.0.1:4000")
+    let bind_addr = "127.0.0.1:4000";
+    let listener = tokio::net::TcpListener::bind(bind_addr)
         .await
-        .unwrap();
+        .with_context(|| format!(
+            "Failed to bind to {bind_addr}. Is another process using this port?\n\
+             Try closing any application that might be listening on port 4000 and rerun the installer."
+        ))?;
 
     println!("Listening on http://{}", listener.local_addr().unwrap());
     println!("Please open above URL in your browser and log into the router to continue.");