Add metadata display and optimize CPU usage

Metadata features:
- Display artist, album, title in bottom status bar (left-aligned)
- Display bitrate, codec, sample rate in bottom status bar (right-aligned)
- Fetch metadata from MPV using metadata/by-key properties
- Support both lowercase and uppercase metadata tags

Performance optimizations:
- Split property updates: fast updates (position/duration) vs slow (metadata)
- Update metadata only every 2 seconds instead of every 100ms
- Skip MPV property updates entirely when stopped
- Conditional UI redraws - only when state actually changes
- Variable poll rate: 200ms when stopped, 100ms when playing
- Position update throttling (0.5s minimum change)
- Reduces CPU usage from constant 10 FPS to ~0.1 FPS when idle

src/player/mod.rs

@@ -15,6 +15,12 @@ pub struct Player {
     duration: f64,
     is_paused: bool,
     is_idle: bool,
+    pub media_title: Option<String>,
+    pub artist: Option<String>,
+    pub album: Option<String>,
+    pub audio_codec: Option<String>,
+    pub audio_bitrate: Option<f64>,
+    pub sample_rate: Option<i64>,
 }
 
 impl Player {
@@ -50,6 +56,12 @@ impl Player {
             duration: 0.0,
             is_paused: false,
             is_idle: true,
+            media_title: None,
+            artist: None,
+            album: None,
+            audio_codec: None,
+            audio_bitrate: None,
+            sample_rate: None,
         })
     }
 
@@ -101,6 +113,12 @@ impl Player {
         self.position = 0.0;
         self.duration = 0.0;
         self.is_paused = false;
+        self.media_title = None;
+        self.artist = None;
+        self.album = None;
+        self.audio_codec = None;
+        self.audio_bitrate = None;
+        self.sample_rate = None;
 
         // Wait for socket to be created and mpv to be ready
         std::thread::sleep(Duration::from_millis(800));
@@ -230,6 +248,63 @@ impl Player {
         }
     }
 
+    pub fn update_metadata(&mut self) {
+        // Try to get artist directly
+        if let Some(val) = self.get_property("metadata/by-key/artist") {
+            self.artist = val.as_str().map(|s| s.to_string());
+        }
+        // Fallback to ARTIST (uppercase)
+        if self.artist.is_none() {
+            if let Some(val) = self.get_property("metadata/by-key/ARTIST") {
+                self.artist = val.as_str().map(|s| s.to_string());
+            }
+        }
+
+        // Try to get album directly
+        if let Some(val) = self.get_property("metadata/by-key/album") {
+            self.album = val.as_str().map(|s| s.to_string());
+        }
+        // Fallback to ALBUM (uppercase)
+        if self.album.is_none() {
+            if let Some(val) = self.get_property("metadata/by-key/ALBUM") {
+                self.album = val.as_str().map(|s| s.to_string());
+            }
+        }
+
+        // Try to get title directly
+        if let Some(val) = self.get_property("metadata/by-key/title") {
+            self.media_title = val.as_str().map(|s| s.to_string());
+        }
+        // Fallback to TITLE (uppercase)
+        if self.media_title.is_none() {
+            if let Some(val) = self.get_property("metadata/by-key/TITLE") {
+                self.media_title = val.as_str().map(|s| s.to_string());
+            }
+        }
+
+        // Final fallback to media-title if metadata doesn't have title
+        if self.media_title.is_none() {
+            if let Some(val) = self.get_property("media-title") {
+                self.media_title = val.as_str().map(|s| s.to_string());
+            }
+        }
+
+        // Update audio codec
+        if let Some(val) = self.get_property("audio-codec-name") {
+            self.audio_codec = val.as_str().map(|s| s.to_string());
+        }
+
+        // Update audio bitrate (convert from bps to kbps)
+        if let Some(val) = self.get_property("audio-bitrate") {
+            self.audio_bitrate = val.as_f64().map(|b| b / 1000.0);
+        }
+
+        // Update sample rate
+        if let Some(val) = self.get_property("audio-params/samplerate") {
+            self.sample_rate = val.as_i64();
+        }
+    }
+
     pub fn get_position(&self) -> Option<f64> {
         Some(self.position)
     }