[feat](trx-rs): add AIS decoder mode and frontend

Add dual-channel AIS decode support across the SoapySDR backend, server decode pipeline, and frontend plugins, including the new AIS tab, live bar, and map filtering.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-server/trx-backend/trx-backend-ft817/src/lib.rs

@@ -195,6 +195,7 @@ impl Ft817 {
                     RigMode::AM,
                     RigMode::WFM,
                     RigMode::FM,
+                    RigMode::AIS,
                     RigMode::DIG,
                     RigMode::PKT,
                 ],
@@ -588,6 +589,7 @@ fn encode_mode(mode: &RigMode) -> u8 {
         RigMode::AM => 0x04,
         RigMode::WFM => 0x06,
         RigMode::FM => 0x08,
+        RigMode::AIS => 0x08,
         RigMode::DIG => 0x0A,
         RigMode::PKT => 0x0C,
         RigMode::Other(_) => 0x00,