[refactor](trx-core): restrict state data fields to pub(crate) with accessors

Make ReadyStateData and TransmittingStateData fields pub(crate) to
prevent external mutation that could bypass state machine invariants.
Add constructors and getter methods for external consumers.

https://claude.ai/code/session_01XzurkeuUmamBuhQwxVy7T4
Signed-off-by: Claude <noreply@anthropic.com>

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

@@ -96,26 +96,115 @@ pub enum RigMachineState {
 }
 
 /// Data held when rig is in Ready state.
+///
+/// Fields are crate-private to prevent external mutation that could bypass
+/// state machine invariants. Use the constructor and accessor methods.
 #[derive(Debug, Clone, Serialize)]
 pub struct ReadyStateData {
-    pub rig_info: RigInfo,
-    pub freq: Freq,
-    pub mode: RigMode,
-    pub vfo: Option<RigVfo>,
-    pub rx: Option<RigRxStatus>,
-    pub tx_limit: Option<u8>,
-    pub locked: bool,
+    pub(crate) rig_info: RigInfo,
+    pub(crate) freq: Freq,
+    pub(crate) mode: RigMode,
+    pub(crate) vfo: Option<RigVfo>,
+    pub(crate) rx: Option<RigRxStatus>,
+    pub(crate) tx_limit: Option<u8>,
+    pub(crate) locked: bool,
+}
+
+impl ReadyStateData {
+    pub fn new(
+        rig_info: RigInfo,
+        freq: Freq,
+        mode: RigMode,
+        vfo: Option<RigVfo>,
+        rx: Option<RigRxStatus>,
+        tx_limit: Option<u8>,
+        locked: bool,
+    ) -> Self {
+        Self {
+            rig_info,
+            freq,
+            mode,
+            vfo,
+            rx,
+            tx_limit,
+            locked,
+        }
+    }
+
+    pub fn rig_info(&self) -> &RigInfo {
+        &self.rig_info
+    }
+    pub fn freq(&self) -> Freq {
+        self.freq
+    }
+    pub fn mode(&self) -> &RigMode {
+        &self.mode
+    }
+    pub fn vfo(&self) -> Option<&RigVfo> {
+        self.vfo.as_ref()
+    }
+    pub fn rx(&self) -> Option<&RigRxStatus> {
+        self.rx.as_ref()
+    }
+    pub fn tx_limit(&self) -> Option<u8> {
+        self.tx_limit
+    }
+    pub fn is_locked(&self) -> bool {
+        self.locked
+    }
 }
 
 /// Data held when rig is in Transmitting state.
+///
+/// Fields are crate-private to prevent external mutation that could bypass
+/// state machine invariants. Use the constructor and accessor methods.
 #[derive(Debug, Clone, Serialize)]
 pub struct TransmittingStateData {
-    pub rig_info: RigInfo,
-    pub freq: Freq,
-    pub mode: RigMode,
-    pub vfo: Option<RigVfo>,
-    pub tx: Option<RigTxStatus>,
-    pub locked: bool,
+    pub(crate) rig_info: RigInfo,
+    pub(crate) freq: Freq,
+    pub(crate) mode: RigMode,
+    pub(crate) vfo: Option<RigVfo>,
+    pub(crate) tx: Option<RigTxStatus>,
+    pub(crate) locked: bool,
+}
+
+impl TransmittingStateData {
+    pub fn new(
+        rig_info: RigInfo,
+        freq: Freq,
+        mode: RigMode,
+        vfo: Option<RigVfo>,
+        tx: Option<RigTxStatus>,
+        locked: bool,
+    ) -> Self {
+        Self {
+            rig_info,
+            freq,
+            mode,
+            vfo,
+            tx,
+            locked,
+        }
+    }
+
+    pub fn rig_info(&self) -> &RigInfo {
+        &self.rig_info
+    }
+    pub fn freq(&self) -> Freq {
+        self.freq
+    }
+    pub fn mode(&self) -> &RigMode {
+        &self.mode
+    }
+    pub fn vfo(&self) -> Option<&RigVfo> {
+        self.vfo.as_ref()
+    }
+    pub fn tx(&self) -> Option<&RigTxStatus> {
+        self.tx.as_ref()
+    }
+    pub fn is_locked(&self) -> bool {
+        self.locked
+    }
 }
 
 impl fmt::Display for RigMachineState {