Update AudioFlinger docs

Author: ThomasFarstrike

docs/frameworks/audioflinger.md

@@ -25,15 +25,32 @@ AudioFlinger provides:
 
 ## Quick Start
 
+### Initialization
+
+AudioFlinger uses a singleton pattern. Initialize it once at startup with your hardware configuration:
+
+```python
+from mpos.audio.audioflinger import AudioFlinger
+
+# Initialize with I2S and buzzer (typical Fri3d badge setup)
+i2s_pins = {'sck': 2, 'ws': 47, 'sd': 16, 'sd_in': 15}
+buzzer = machine.PWM(machine.Pin(46))
+AudioFlinger(i2s_pins=i2s_pins, buzzer_instance=buzzer)
+
+# After initialization, use class methods directly (no .get() needed)
+AudioFlinger.play_wav("music.wav")
+AudioFlinger.set_volume(70)
+```
+
 ### Playing WAV Files
 
 ```python
 from mpos import Activity
-import mpos.audio.audioflinger as AudioFlinger
+from mpos.audio.audioflinger import AudioFlinger
 
 class MusicPlayerActivity(Activity):
     def onCreate(self):
-        # Play a music file
+        # Play a music file (class method - no .get() needed)
         success = AudioFlinger.play_wav(
             "M:/sdcard/music/song.wav",
             stream_type=AudioFlinger.STREAM_MUSIC,
@@ -53,6 +70,8 @@ class MusicPlayerActivity(Activity):
 ### Playing RTTTL Ringtones
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # Play notification sound via buzzer
 rtttl = "Nokia:d=4,o=5,b=225:8e6,8d6,8f#,8g#,8c#6,8b,d,8p,8b,8a,8c#,8e"
 AudioFlinger.play_rtttl(
@@ -75,6 +94,8 @@ Nokia:d=4,o=5,b=225:8e6,8d6,8f#,8g#
 ### Volume Control
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # Set volume (0-100)
 AudioFlinger.set_volume(70)
 
@@ -97,7 +118,7 @@ AudioFlinger supports recording audio from an I2S microphone to WAV files.
 ### Basic Recording
 
 ```python
-import mpos.audio.audioflinger as AudioFlinger
+from mpos.audio.audioflinger import AudioFlinger
 
 # Check if microphone is available
 if AudioFlinger.has_microphone():
@@ -149,7 +170,7 @@ if AudioFlinger.is_playing():
 
 ```python
 from mpos import Activity
-import mpos.audio.audioflinger as AudioFlinger
+from mpos.audio.audioflinger import AudioFlinger
 import lvgl as lv
 import time
 
@@ -233,6 +254,8 @@ AudioFlinger implements a 3-tier priority-based audio focus system inspired by A
 ### Example: Priority in Action
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # Start playing music (priority 0)
 AudioFlinger.play_wav("music.wav", stream_type=AudioFlinger.STREAM_MUSIC)
 
@@ -300,7 +323,7 @@ Audio device preference is configured in the Settings app under **"Advanced Sett
 
 ```python
 from mpos import Activity
-import mpos.audio.audioflinger as AudioFlinger
+from mpos.audio.audioflinger import AudioFlinger
 import lvgl as lv
 
 class SimpleMusicPlayerActivity(Activity):
@@ -472,6 +495,8 @@ Check if buzzer is available for RTTTL playback.
 4. Use equal or higher priority stream type
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # Check if playback was rejected
 success = AudioFlinger.play_wav("sound.wav", stream_type=AudioFlinger.STREAM_MUSIC)
 if not success:
@@ -582,25 +607,32 @@ ffmpeg -i input.wav -acodec pcm_s16le -ar 22050 -ac 1 output.wav
 **Possible causes:**
 
 1. **No microphone available**
-   ```python
-   if not AudioFlinger.has_microphone():
-       print("No microphone on this device")
-   ```
+    ```python
+    from mpos.audio.audioflinger import AudioFlinger
+    
+    if not AudioFlinger.has_microphone():
+        print("No microphone on this device")
+    ```
 
 2. **Currently playing audio**
-   ```python
-   # I2S can only be TX or RX, not both
-   if AudioFlinger.is_playing():
-       AudioFlinger.stop()
-       time.sleep_ms(100)  # Wait for cleanup
-   AudioFlinger.record_wav("recording.wav")
-   ```
+    ```python
+    from mpos.audio.audioflinger import AudioFlinger
+    import time
+    
+    # I2S can only be TX or RX, not both
+    if AudioFlinger.is_playing():
+        AudioFlinger.stop()
+        time.sleep_ms(100)  # Wait for cleanup
+    AudioFlinger.record_wav("recording.wav")
+    ```
 
 3. **Already recording**
-   ```python
-   if AudioFlinger.is_recording():
-       print("Already recording")
-   ```
+    ```python
+    from mpos.audio.audioflinger import AudioFlinger
+    
+    if AudioFlinger.is_recording():
+        print("Already recording")
+    ```
 
 4. **Wrong board** - Waveshare doesn't have a microphone
 
@@ -635,6 +667,8 @@ ffmpeg -i input.wav -acodec pcm_s16le -ar 44100 -ac 2 output.wav
 AudioFlinger runs in a separate thread, so playback doesn't block the UI:
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # This doesn't block - returns immediately
 AudioFlinger.play_wav("long_song.wav", stream_type=AudioFlinger.STREAM_MUSIC)
 
@@ -663,6 +697,8 @@ On desktop builds (Linux/macOS), AudioFlinger provides simulated recording for t
 This allows testing the Sound Recorder app and other recording features without hardware.
 
 ```python
+from mpos.audio.audioflinger import AudioFlinger
+
 # Desktop simulation is automatic when machine.I2S is not available
 # The generated WAV file contains a 440Hz tone
 AudioFlinger.record_wav("test.wav", duration_ms=5000)