[feat](trx-rs): add FT2 decoder support (wired to FT4)

Mirrors the FT4 implementation across the full stack. The trx-ft8
crate wires Ft8Decoder::new_ft2() to FTX_PROTOCOL_FT4 as a
placeholder pending a dedicated FT2 implementation.

Changes:
- trx-ft8: Ft8Decoder::new_ft2() delegates to with_protocol(Ft4)
- trx-core: DecodedMessage::Ft2, AUDIO_MSG_FT2_DECODE (0x15),
  ft2_decode_enabled/ft2_decode_reset_seq state, SetFt2DecodeEnabled/
  ResetFt2Decoder commands, protocol mapping
- trx-server: DecoderHistories::ft2, run_ft2_decoder (7.5s slots),
  run_background_ft2_decoder, history push/replay, decoder task spawn
- trx-frontend-http: ft2_history in FrontendRuntimeContext,
  toggle/clear endpoints, /ft2.js route, bookmark/scheduler/background
  decode support, DecodeHistoryPayload ft2 field
- web: ft2.js plugin (3.75s period timer), FT2 subtab in index.html,
  FT2 map source (distinct hue), app.js dispatch, decode-history-worker
  HISTORY_GROUP_KEYS, bookmarks read/write/apply

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-core/src/audio.rs

@@ -64,6 +64,8 @@ pub const AUDIO_MSG_VCHAN_DESTROYED: u8 = 0x12;
 pub const AUDIO_MSG_VCHAN_BW: u8 = 0x13;
 /// Server → client: FT4 decoded message (JSON `DecodedMessage::Ft4`).
 pub const AUDIO_MSG_FT4_DECODE: u8 = 0x14;
+/// Server → client: FT2 decoded message (JSON `DecodedMessage::Ft2`).
+pub const AUDIO_MSG_FT2_DECODE: u8 = 0x15;
 
 /// Maximum payload size for normal messages (1 MB).
 const MAX_PAYLOAD_SIZE: u32 = 1_048_576;

src/trx-core/src/decode.rs

@@ -24,6 +24,8 @@ pub enum DecodedMessage {
     Ft8(Ft8Message),
     #[serde(rename = "ft4")]
     Ft4(Ft8Message),
+    #[serde(rename = "ft2")]
+    Ft2(Ft8Message),
     #[serde(rename = "wspr")]
     Wspr(WsprMessage),
 }

src/trx-core/src/rig/command.rs

@@ -29,12 +29,14 @@ pub enum RigCommand {
     SetCwToneHz(u32),
     SetFt8DecodeEnabled(bool),
     SetFt4DecodeEnabled(bool),
+    SetFt2DecodeEnabled(bool),
     SetWsprDecodeEnabled(bool),
     ResetAprsDecoder,
     ResetHfAprsDecoder,
     ResetCwDecoder,
     ResetFt8Decoder,
     ResetFt4Decoder,
+    ResetFt2Decoder,
     ResetWsprDecoder,
     SetBandwidth(u32),
     SetFirTaps(u32),

src/trx-core/src/rig/controller/handlers.rs

@@ -510,6 +510,7 @@ pub fn command_from_rig_command(cmd: RigCommand) -> Box<dyn RigCommandHandler> {
         | RigCommand::SetCwToneHz(_)
         | RigCommand::SetFt8DecodeEnabled(_)
         | RigCommand::SetFt4DecodeEnabled(_)
+        | RigCommand::SetFt2DecodeEnabled(_)
         | RigCommand::SetWsprDecodeEnabled(_)
         | RigCommand::SetHfAprsDecodeEnabled(_)
         | RigCommand::ResetHfAprsDecoder
@@ -517,6 +518,7 @@ pub fn command_from_rig_command(cmd: RigCommand) -> Box<dyn RigCommandHandler> {
         | RigCommand::ResetCwDecoder
         | RigCommand::ResetFt8Decoder
         | RigCommand::ResetFt4Decoder
+        | RigCommand::ResetFt2Decoder
         | RigCommand::ResetWsprDecoder
         | RigCommand::SetBandwidth(_)
         | RigCommand::SetFirTaps(_)

src/trx-core/src/rig/state.rs

@@ -40,6 +40,8 @@ pub struct RigState {
     #[serde(default)]
     pub ft4_decode_enabled: bool,
     #[serde(default)]
+    pub ft2_decode_enabled: bool,
+    #[serde(default)]
     pub wspr_decode_enabled: bool,
     #[serde(default)]
     pub cw_auto: bool,
@@ -70,6 +72,8 @@ pub struct RigState {
     #[serde(default, skip_serializing)]
     pub ft4_decode_reset_seq: u64,
     #[serde(default, skip_serializing)]
+    pub ft2_decode_reset_seq: u64,
+    #[serde(default, skip_serializing)]
     pub wspr_decode_reset_seq: u64,
 }
 
@@ -148,6 +152,7 @@ impl RigState {
             cw_decode_enabled: true,
             ft8_decode_enabled: false,
             ft4_decode_enabled: false,
+            ft2_decode_enabled: false,
             wspr_decode_enabled: false,
             cw_auto: true,
             cw_wpm: 15,
@@ -160,6 +165,7 @@ impl RigState {
             cw_decode_reset_seq: 0,
             ft8_decode_reset_seq: 0,
             ft4_decode_reset_seq: 0,
+            ft2_decode_reset_seq: 0,
             wspr_decode_reset_seq: 0,
         }
     }
@@ -217,6 +223,7 @@ impl RigState {
             cw_tone_hz: snapshot.cw_tone_hz,
             ft8_decode_enabled: snapshot.ft8_decode_enabled,
             ft4_decode_enabled: snapshot.ft4_decode_enabled,
+            ft2_decode_enabled: snapshot.ft2_decode_enabled,
             wspr_decode_enabled: snapshot.wspr_decode_enabled,
             filter: snapshot.filter,
             spectrum: None, // spectrum flows through /api/spectrum, not persistent state
@@ -226,6 +233,7 @@ impl RigState {
             cw_decode_reset_seq: 0,
             ft8_decode_reset_seq: 0,
             ft4_decode_reset_seq: 0,
+            ft2_decode_reset_seq: 0,
             wspr_decode_reset_seq: 0,
         }
     }
@@ -261,6 +269,7 @@ impl RigState {
             cw_tone_hz: self.cw_tone_hz,
             ft8_decode_enabled: self.ft8_decode_enabled,
             ft4_decode_enabled: self.ft4_decode_enabled,
+            ft2_decode_enabled: self.ft2_decode_enabled,
             wspr_decode_enabled: self.wspr_decode_enabled,
             filter: self.filter.clone(),
             spectrum: self.spectrum.clone(),
@@ -427,6 +436,8 @@ pub struct RigSnapshot {
     #[serde(default)]
     pub ft4_decode_enabled: bool,
     #[serde(default)]
+    pub ft2_decode_enabled: bool,
+    #[serde(default)]
     pub wspr_decode_enabled: bool,
     #[serde(default)]
     pub cw_auto: bool,