feat: live ESP32 CSI pipeline + auto-connect WebSocket

- Add auto-connect to local sensing server WebSocket (ws://localhost:8765)
- Demo shows "Live ESP32" when connected to real CSI data
- Add build_firmware.ps1 for native Windows ESP-IDF builds (no Docker)
- Add read_serial.ps1 for ESP32 serial monitor

Pipeline: ESP32 → UDP:5005 → sensing-server → WS:8765 → browser demo

Co-Authored-By: claude-flow <ruv@ruv.net>

firmware/esp32-csi-node/build_firmware.ps1

@@ -0,0 +1,31 @@
+# Remove MSYS environment variables that trigger ESP-IDF's MinGW rejection
+Remove-Item env:MSYSTEM -ErrorAction SilentlyContinue
+Remove-Item env:MSYSTEM_CARCH -ErrorAction SilentlyContinue
+Remove-Item env:MSYSTEM_CHOST -ErrorAction SilentlyContinue
+Remove-Item env:MSYSTEM_PREFIX -ErrorAction SilentlyContinue
+Remove-Item env:MINGW_CHOST -ErrorAction SilentlyContinue
+Remove-Item env:MINGW_PACKAGE_PREFIX -ErrorAction SilentlyContinue
+Remove-Item env:MINGW_PREFIX -ErrorAction SilentlyContinue
+
+$env:IDF_PATH = "C:\Users\ruv\esp\v5.4\esp-idf"
+$env:IDF_TOOLS_PATH = "C:\Espressif\tools"
+$env:IDF_PYTHON_ENV_PATH = "C:\Espressif\tools\python\v5.4\venv"
+$env:PATH = "C:\Espressif\tools\xtensa-esp-elf\esp-14.2.0_20241119\xtensa-esp-elf\bin;C:\Espressif\tools\cmake\3.30.2\cmake-3.30.2-windows-x86_64\bin;C:\Espressif\tools\ninja\1.12.1;C:\Espressif\tools\ccache\4.10.2\ccache-4.10.2-windows-x86_64;C:\Espressif\tools\idf-exe\1.0.3;C:\Espressif\tools\python\v5.4\venv\Scripts;$env:PATH"
+
+Set-Location "C:\Users\ruv\Projects\wifi-densepose\firmware\esp32-csi-node"
+
+$python = "$env:IDF_PYTHON_ENV_PATH\Scripts\python.exe"
+$idf = "$env:IDF_PATH\tools\idf.py"
+
+Write-Host "=== Cleaning stale build cache ==="
+& $python $idf fullclean
+
+Write-Host "=== Building firmware (SSID=ruv.net, target=192.168.1.20:5005) ==="
+& $python $idf build
+
+if ($LASTEXITCODE -eq 0) {
+    Write-Host "=== Build succeeded! Flashing to COM7 ==="
+    & $python $idf -p COM7 flash
+} else {
+    Write-Host "=== Build failed with exit code $LASTEXITCODE ==="
+}

firmware/esp32-csi-node/read_serial.ps1

@@ -0,0 +1,14 @@
+$p = New-Object System.IO.Ports.SerialPort('COM7', 115200)
+$p.ReadTimeout = 5000
+$p.Open()
+Start-Sleep -Milliseconds 200
+
+for ($i = 0; $i -lt 60; $i++) {
+    try {
+        $line = $p.ReadLine()
+        Write-Host $line
+    } catch {
+        break
+    }
+}
+$p.Close()