[fix](trx-wefax): allow WEFAX decoder to run in DIG mode

DIG mode provides the same SSB audio as USB, so WEFAX reception works
there. Added DIG to both the decoder registry active_modes and the
server-side mode gate.

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

src/trx-protocol/src/decoders.rs

@@ -134,7 +134,7 @@ pub const DECODER_REGISTRY: &[DecoderDescriptor] = &[
         id: "wefax",
         label: "WEFAX",
         activation: DecoderActivation::Toggle,
-        active_modes: &["USB", "LSB", "AM"],
+        active_modes: &["USB", "LSB", "AM", "DIG"],
         background_decode: false,
         bookmark_selectable: true,
     },

src/trx-server/src/audio.rs

@@ -2705,7 +2705,7 @@ pub async fn run_wefax_decoder(
     let mut last_reset_seq: u64 = 0;
 
     let is_wefax_mode = |mode: &RigMode| {
-        matches!(mode, RigMode::USB | RigMode::LSB | RigMode::AM)
+        matches!(mode, RigMode::USB | RigMode::LSB | RigMode::AM | RigMode::DIG)
     };
 
     let mut active = state_rx.borrow().decoders.wefax_decode_enabled