[fix](trx-rs): use cache_dir for recordings and decode logs

Move default output directories from $XDG_DATA_HOME to $XDG_CACHE_HOME
so all runtime data lives under ~/.cache/trx-rs/ consistently.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/decoders/trx-decode-log/src/lib.rs

@@ -25,14 +25,14 @@ use trx_core::decode::{AprsPacket, CwEvent, Ft8Message, WefaxMessage, WsprMessag
 // ---------------------------------------------------------------------------
 
 fn default_decode_logs_dir() -> String {
-    if let Some(data_dir) = dirs::data_dir() {
-        return data_dir
+    if let Some(cache_dir) = dirs::cache_dir() {
+        return cache_dir
             .join("trx-rs")
             .join("decoders")
             .to_string_lossy()
             .to_string();
     }
-    "logs/decoders".to_string()
+    ".cache/trx-rs/decoders".to_string()
 }
 
 /// Server-side decoder file logging configuration.

src/trx-client/trx-frontend/trx-frontend-http/src/recorder.rs

@@ -28,7 +28,7 @@ use tracing::{error, info, warn};
 pub struct RecorderConfig {
     /// Whether the recorder feature is available.
     pub enabled: bool,
-    /// Directory for recorded files. Default: `$XDG_DATA_HOME/trx-rs/recordings/`.
+    /// Directory for recorded files. Default: `$XDG_CACHE_HOME/trx-rs/recordings/`.
     pub output_dir: Option<String>,
     /// Maximum duration of a single recording in seconds. None = unlimited.
     pub max_duration_secs: Option<u64>,
@@ -49,8 +49,8 @@ impl RecorderConfig {
         if let Some(ref dir) = self.output_dir {
             PathBuf::from(dir)
         } else {
-            dirs::data_dir()
-                .unwrap_or_else(|| PathBuf::from("."))
+            dirs::cache_dir()
+                .unwrap_or_else(|| PathBuf::from(".cache"))
                 .join("trx-rs")
                 .join("recordings")
         }