feat: SDD workflow — test sync, song generation + validation, ReaScript hybrid pipeline

- compose-test-sync: fix 3 failing tests (NOTE_TO_MIDI, DrumLoopAnalyzer mock, section name)
- generate-song: CLI wrapper + RPP validator (6 structural checks) + 4 e2e tests
- reascript-hybrid: ReaScriptGenerator + command protocol + CLI + 16 unit tests
- 110/110 tests passing
- Full SDD cycle (propose→spec→design→tasks→apply→verify) for all 3 changes

scripts/generate.py

@@ -0,0 +1,63 @@
+"""REAPER .rpp song generator — thin CLI wrapper around compose.main().
+
+Usage:
+    python scripts/generate.py --bpm 95 --key Am --output output/song.rpp --seed 42
+"""
+
+from __future__ import annotations
+
+import argparse
+import sys
+from pathlib import Path
+
+_ROOT = Path(__file__).parent.parent
+sys.path.insert(0, str(_ROOT))
+import compose
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Generate a REAPER .rpp reggaeton song.")
+    parser.add_argument("--bpm", type=float, default=95, help="BPM (default: 95)")
+    parser.add_argument("--key", default="Am", help="Musical key (default: Am)")
+    parser.add_argument(
+        "--output", default="output/song.rpp", help="Output .rpp path (default: output/song.rpp)"
+    )
+    parser.add_argument("--seed", type=int, default=42, help="Random seed (default: 42)")
+    parser.add_argument(
+        "--validate", action="store_true", help="Run validator after generation"
+    )
+    args = parser.parse_args()
+
+    # BPM validation
+    if args.bpm <= 0:
+        raise ValueError("bpm must be > 0")
+
+    # Ensure output directory exists
+    output_path = Path(args.output)
+    output_path.parent.mkdir(parents=True, exist_ok=True)
+
+    # Delegate to compose.main() — set sys.argv so compose's argparse works
+    sys.argv = [
+        sys.argv[0],
+        "--bpm", str(args.bpm),
+        "--key", args.key,
+        "--output", str(output_path),
+        "--seed", str(args.seed),
+    ]
+    compose.main()
+
+    # Post-generation validation
+    if args.validate:
+        from src.validator.rpp_validator import validate_rpp_output
+
+        errors = validate_rpp_output(str(output_path), expected_bpm=args.bpm, expected_bars=52)
+        if errors:
+            print("Validation errors:", file=sys.stderr)
+            for err in errors:
+                print(f"  - {err}", file=sys.stderr)
+            sys.exit(1)
+        print("Validation passed.", file=sys.stderr)
+
+
+if __name__ == "__main__":
+    main()