chore(phase-0): stabilise foundation for Studio build

- Extract WAV assembly (buildWav, mergeFloat32Arrays, decodeFloat32Chunk,
  SAMPLE_RATE) into web/lib/audio/wav.ts so it can be reused by the
  Studio playback engine and library waveform previews
- Add server/waveform.py with compute_peaks() / write_peaks() — reads
  any WAV, mixes to mono, returns min/max peak arrays matching the
  WaveformPeaks TypeScript type
- Add server/ids.py with prefixed URL-safe ID helpers (gen_id, proj_id,
  asset_id, etc.) using stdlib secrets — no new dependency
- Add docs/studio-build-plan.md — full execution spec covering stack
  decisions, data models, API contract, component hierarchy, phase
  breakdown and acceptance criteria
- Ignore data/ directory (generated audio, waveforms, SQLite DB)

server/ids.py

@@ -0,0 +1,35 @@
+"""Stable, URL-safe ID generation for VibePod entities."""
+
+import secrets
+
+
+def _make_id(prefix: str) -> str:
+    return f"{prefix}_{secrets.token_urlsafe(8)}"
+
+
+def gen_id() -> str:
+    return _make_id("gen")
+
+
+def proj_id() -> str:
+    return _make_id("proj")
+
+
+def asset_id() -> str:
+    return _make_id("asset")
+
+
+def track_id() -> str:
+    return _make_id("track")
+
+
+def clip_id() -> str:
+    return _make_id("clip")
+
+
+def block_id() -> str:
+    return _make_id("block")
+
+
+def take_id() -> str:
+    return _make_id("take")