P1-R3: Initial project infrastructure

- Project directory structure: docs/, src/, build/, recipes/, scripts/, wiki/
- README.md with project overview and status
- .editorconfig for consistent code style
- .gitignore for Python, C/C++, kernel, and build artifacts
- docs/research/: system research report + base OS decision
- docs/audio-stack-config.md: audio stack configuration notes
- config/: JACK, ALSA, CPU performance configs
- Preserved research from P1-R1 and P1-R2 tasks

config/jackd.service

@@ -0,0 +1,43 @@
+[Unit]
+Description=JACK2 Audio Server
+After=sound.target network.target
+Wants=sound.target
+
+[Service]
+Type=simple
+User=pi
+Group=audio
+Environment=JACK_NO_AUDIO_RESERVATION=1
+Environment=JACK_PROMISCUOUS_SERVER=1
+
+# Real-time scheduling
+LimitRTPRIO=99
+LimitMEMLOCK=infinity
+LimitNICE=-20
+
+# CPU affinity — pin JACK server to audio cores 1-3
+CPUAffinity=1-3
+
+# I/O scheduling — realtime class
+IOSchedulingClass=realtime
+IOSchedulingPriority=0
+
+# JACK daemon command
+ExecStart=/usr/bin/jackd \
+    -P 70 \
+    -t 2000 \
+    -d alsa \
+    -d hw:USB \
+    -r 48000 \
+    -p 128 \
+    -n 3 \
+    -M \
+    -X seq \
+    -S
+
+# Restart on crash (but not on clean shutdown)
+Restart=on-failure
+RestartSec=2
+
+[Install]
+WantedBy=multi-user.target