v0.2.1: Fix cancel key (Escape) being swallowed globally

The cancel key was consumed by rdev::grab at all times, not just during
recording/transcribing. This made the Escape key unusable system-wide
while Mouth was running. Now the cancel key only gets swallowed when
Mouth is actively recording or transcribing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/shared_state.rs

@@ -1,9 +1,13 @@
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::RwLock;
 use std::time::Instant;
 
 /// Thread-safe shared state accessible by the coordinator, IPC listener, and tray icon.
 pub struct SharedState {
     pub state: RwLock<String>,
+    /// True when recording or transcribing — the hotkey listener uses this to
+    /// decide whether to swallow the cancel key.
+    pub is_active: AtomicBool,
     pub model: String,
     pub accelerator: String,
     pub started_at: Instant,
@@ -13,6 +17,7 @@ impl SharedState {
     pub fn new(model: String, accelerator: String) -> Self {
         Self {
             state: RwLock::new("idle".to_string()),
+            is_active: AtomicBool::new(false),
             model,
             accelerator,
             started_at: Instant::now(),
@@ -23,6 +28,7 @@ impl SharedState {
         if let Ok(mut s) = self.state.write() {
             *s = state.to_string();
         }
+        self.is_active.store(state != "idle", Ordering::Release);
     }
 
     pub fn get_state(&self) -> String {