feat: full reggaeton song generator with master chain, sends, clap, vocal, drumloop

- Add master FXCHAIN with Pro-Q 3, Pro-C 2, Pro-L 2 on master track
- Add AUXRECV sends routing to Reverb/Delay return tracks
- Add clap track with CLAP_DEMBOW pattern
- Add vocal track with sample selection per section
- Add drumloop layer with loop detection
- Add track colors per role for visual organization
- Randomize chord progressions from genre config (5 options)
- Add master_plugins and send_level fields to schema
- Add _build_master_fxchain() and AUXRECV rendering to RPPBuilder
- 72 tests passing, RPP generates with 12 tracks, 18 sends, 20 plugins

src/composer/rhythm.py

@@ -349,6 +349,20 @@ def clap_24_notes(
     return _apply_groove({CH_CL: notes}, groove_strength)
 
 
+def generate_clap_pattern(
+    bars: int,
+    velocity_mult: float = 1.0,
+    density: float = 1.0,
+    groove_strength: float = 0.0,
+) -> dict[int, list[dict]]:
+    """Generate clap pattern using CLAP_DEMBOW.
+
+    Snare on beats 2, 3.5 — standard reggaeton clap.
+    Returns {CH_CL: [notes...]}.
+    """
+    return clap_24_notes(bars, velocity_mult, density, groove_strength)
+
+
 # ---------------------------------------------------------------------------
 # Percussion generators
 # ---------------------------------------------------------------------------