[feat](trx-app): support combined trx-rs.toml config file

Both trx-server and trx-client now look for a combined trx-rs.toml
with [trx-server] and [trx-client] section headers respectively,
falling back to per-binary config files as before.

Search order per tier: combined trx-rs.toml → flat per-binary file,
checked in CWD, ~/.config/trx-rs/, and /etc/trx-rs/.

--print-config now outputs the config under the appropriate section
header so the combined file can be generated directly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-server/src/config.rs

@@ -691,6 +691,46 @@ impl ServerConfig {
 
         toml::to_string_pretty(&example).unwrap_or_default()
     }
+
+    /// Generate an example configuration wrapped under the `[trx-server]`
+    /// section header, suitable for use in a combined `trx-rs.toml` file.
+    pub fn example_combined_toml() -> String {
+        #[derive(serde::Serialize)]
+        struct Wrapper {
+            #[serde(rename = "trx-server")]
+            inner: ServerConfig,
+        }
+        let example = ServerConfig {
+            general: GeneralConfig {
+                callsign: Some("N0CALL".to_string()),
+                log_level: Some("info".to_string()),
+                latitude: Some(52.2297),
+                longitude: Some(21.0122),
+            },
+            rig: RigConfig {
+                model: Some("ft817".to_string()),
+                initial_freq_hz: 144_300_000,
+                initial_mode: RigMode::USB,
+                access: AccessConfig {
+                    access_type: Some("serial".to_string()),
+                    port: Some("/dev/ttyUSB0".to_string()),
+                    baud: Some(9600),
+                    host: None,
+                    tcp_port: None,
+                    args: None,
+                },
+            },
+            behavior: BehaviorConfig::default(),
+            listen: ListenConfig::default(),
+            audio: AudioConfig::default(),
+            pskreporter: PskReporterConfig::default(),
+            aprsfi: AprsFiConfig::default(),
+            decode_logs: DecodeLogsConfig::default(),
+            sdr: SdrConfig::default(),
+            rigs: Vec::new(),
+        };
+        toml::to_string_pretty(&Wrapper { inner: example }).unwrap_or_default()
+    }
 }
 
 fn validate_log_level(level: Option<&str>) -> Result<(), String> {
@@ -789,6 +829,10 @@ impl ConfigFile for ServerConfig {
         "server.toml"
     }
 
+    fn combined_key() -> Option<&'static str> {
+        Some("trx-server")
+    }
+
     fn default_search_paths() -> Vec<PathBuf> {
         let mut paths = Vec::new();
         paths.push(PathBuf::from("trx-server.toml"));

src/trx-server/src/main.rs

@@ -663,7 +663,7 @@ async fn main() -> DynResult<()> {
     let cli = Cli::parse();
 
     if cli.print_config {
-        println!("{}", ServerConfig::example_toml());
+        println!("{}", ServerConfig::example_combined_toml());
         return Ok(());
     }