refactor: migrate from FL Studio to REAPER with rpp library

Replace FL Studio binary .flp output with REAPER text-based .rpp output
using the rpp Python library (Perlence/rpp).

- Add core/schema.py: DAW-agnostic data types (SongDefinition, TrackDef,
  ClipDef, MidiNote, PluginDef)
- Add reaper_builder/: RPP file generation via rpp.Element + headless
  render via reaper.exe CLI
- Add composer/converters.py: bridge rhythm.py/melodic.py note dicts
  to core.schema MidiNote objects
- Rewrite scripts/compose.py: real generator pipeline with --render flag
- Delete src/flp_builder/, src/scanner/, mcp/, flstudio-mcp/, old scripts
- Add 40 passing tests (schema, builder, converters, compose, render)

src/composer/melodic.py

@@ -4,6 +4,8 @@ All generators return list[dict] with format {pos, len, key, vel}.
 Designed to feed MelodicTrack notes in SongDefinition.
 """
 
+import random
+
 # ---------------------------------------------------------------------------
 # Scale definitions
 # ---------------------------------------------------------------------------
@@ -52,6 +54,18 @@ def _clamp_vel(v: int) -> int:
     return max(1, min(127, v))
 
 
+def _apply_humanize(notes, humanize):
+    """Apply humanization (velocity jitter + position nudge) to note list."""
+    if humanize <= 0:
+        return notes
+    jitter = humanize * 5
+    nudge = humanize * 0.03
+    for n in notes:
+        n["vel"] = _clamp_vel(int(n["vel"] + random.uniform(-jitter, jitter)))
+        n["pos"] = max(0, n["pos"] + random.uniform(-nudge, nudge))
+    return notes
+
+
 # ---------------------------------------------------------------------------
 # Bass: tresillo
 # ---------------------------------------------------------------------------
@@ -61,6 +75,7 @@ def bass_tresillo(
     bars: int,
     octave: int = 3,
     velocity_mult: float = 1.0,
+    humanize: float = 0.0,
 ) -> list[dict]:
     """Reggaeton tresillo bass pattern.
 
@@ -90,7 +105,7 @@ def bass_tresillo(
             vel = _clamp_vel(int(vel * velocity_mult))
             notes.append({"pos": o + pos, "len": 0.25, "key": key_note, "vel": vel})
 
-    return notes
+    return _apply_humanize(notes, humanize)
 
 
 # ---------------------------------------------------------------------------
@@ -103,6 +118,7 @@ def lead_hook(
     octave: int = 5,
     density: float = 0.6,
     velocity_mult: float = 1.0,
+    humanize: float = 0.0,
 ) -> list[dict]:
     """Simple melodic hook over 4-8 bars.
 
@@ -154,7 +170,7 @@ def lead_hook(
         else:
             pos += 0.5
 
-    return notes
+    return _apply_humanize(notes, humanize)
 
 
 # ---------------------------------------------------------------------------
@@ -166,6 +182,7 @@ def chords_block(
     bars: int,
     octave: int = 4,
     velocity_mult: float = 1.0,
+    humanize: float = 0.0,
 ) -> list[dict]:
     """Blocked chords every 2 beats (half-bar).
 
@@ -231,7 +248,7 @@ def chords_block(
                     "vel": vel,
                 })
 
-    return notes
+    return _apply_humanize(notes, humanize)
 
 
 # ---------------------------------------------------------------------------
@@ -243,6 +260,7 @@ def pad_sustain(
     bars: int,
     octave: int = 4,
     velocity_mult: float = 1.0,
+    humanize: float = 0.0,
 ) -> list[dict]:
     """Long sustained pad notes, one per bar.