Phase 1-4: Audio stack, mixer engine, MIDI, and network API

P2-R1: ALSA + JACK2 low-latency config (scripts, quirks, tuning)
P2-R2: Carla integration (build scripts, 8ch rack config, NAM LV2 support)
P2-R3: Plugin manager, categories, blacklist, NAM model support
P3-R1: Mixer DSP engine (channel strip, routing matrix, bus mgr, automation)
P4-R1: MIDI engine (learn mode, clock sync, HID discovery, mapping store)
P4-R2: Network API (OSC server, FastAPI REST, WebSocket, auth, rate limiter)
P5-R1: Touchscreen UI evaluation + main entry point
docs: Audio stack, Carla integration, MIDI support, UI evaluation
tests: Full test suite (292 passing)

README.md

@@ -25,13 +25,13 @@ RPi4B-based multi-channel real-time audio mixer with custom PREEMPT_RT kernel.
 
 ## Status
 
-**Phase 1: Research & Planning (in progress)**
+**Phase 1-4: Core audio stack + MIDI controller support (in progress)**
 - [x] P1-R1: System Research — USB audio, PREEMPT_RT kernel analysis
 - [x] P1-R2: Base OS Selection — RPiOS Lite 64-bit + custom PREEMPT_RT
-- [ ] P1-R3: Project Infrastructure (current)
-- [ ] P2: Kernel Build — custom PREEMPT_RT kernel compilation
-- [ ] P3: Audio Engine — JACK/PipeWire integration, DSP pipeline
-- [ ] P4: Hardware Integration — USB interface, GPIO control surface
+- [x] P2-R1: ALSA + JACK2 Low-Latency Config
+- [x] P4-R1: MIDI Controller Support — Binding + Learn Mode
+- [ ] P3: Audio Engine — DSP pipeline, mixing engine
+- [ ] P4: Hardware Integration — GPIO control surface
 
 ## Getting Started