Add single-ESP32S3 demo setup for presence detection

Simplified setup for running RuView with just ONE ESP32-S3 board:
- Basic presence detection (room occupancy)
- Motion detection
- Distance estimation

For full pose estimation (17 keypoints), breathing, and heart rate,
2+ nodes are recommended.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

demo-single-esp32s3/README.md

@@ -0,0 +1,122 @@
+# RuView Single ESP32-S3 Demo
+
+A simplified setup for running RuView with just ONE ESP32-S3 board for basic presence detection.
+
+> **Note:** Single-node detection has limited spatial resolution. For full pose estimation (17 keypoints), use 2+ nodes. This demo focuses on **presence detection** - detecting if someone is in the room.
+
+## What You Need
+
+| Item | Cost | Notes |
+|------|------|-------|
+| ESP32-S3 DevKit (8MB flash) | ~$9 | Any ESP32-S3 with 8MB flash works |
+| Micro USB cable | ~$5 | For power + programming |
+| WiFi network | - | 2.4GHz WiFi required |
+
+## Quick Start
+
+### Step 1: Get Pre-built Firmware
+
+Download the latest firmware from releases:
+- Go to: https://github.com/Rudraa-25/RuView/releases
+- Download `esp32-csi-node.bin` (or build from source - see below)
+
+### Step 2: Flash the Firmware
+
+Connect your ESP32-S3 to your PC via USB. Note the COM port (e.g., COM7 on Windows).
+
+```bash
+# Install esptool if you don't have it
+pip install esptool
+
+# Flash the firmware (replace COM7 with your port)
+python -m esptool --chip esp32s3 --port COM7 --baud 460800 \
+  write_flash --flash_mode dio --flash_size 8MB \
+  0x0 release/bootloader.bin \
+  0x8000 release/partition-table.bin \
+  0x10000 release/esp32-csi-node.bin
+```
+
+### Step 3: Provision WiFi
+
+After flashing, provision your WiFi credentials (no reflashing needed):
+
+```bash
+python firmware/esp32-csi-node/provision.py --port COM7 \
+  --ssid "YourWiFiName" --password "YourWiFiPassword" --target-ip 192.168.1.100
+```
+
+### Step 4: Run the Sensing Server
+
+```bash
+# Install dependencies
+pip install -r requirements.txt
+
+# Start the server (single-node mode)
+cargo run -p wifi-densepose-sensing-server -- --http-port 3000 --source single
+```
+
+### Step 5: Open the Dashboard
+
+Navigate to http://localhost:3000 in your browser.
+
+You should see presence detection data flowing in when people are in range of your WiFi router and the ESP32-S3.
+
+## Building from Source (Optional)
+
+If you want to build the firmware yourself:
+
+```bash
+# Using Docker (recommended for Windows)
+MSYS_NO_PATHCONV=1 docker run --rm \
+  -v "$(pwd)/firmware/esp32-csi-node:/project" -w /project \
+  espressif/idf:v5.2 bash -c \
+  "rm -rf build sdkconfig && idf.py set-target esp32s3 && idf.py build"
+
+# Flash the built firmware
+python -m esptool --chip esp32s3 --port COM7 --baud 460800 \
+  write_flash --flash_mode dio --flash_size 8MB \
+  0x0 firmware/esp32-csi-node/build/bootloader/bootloader.bin \
+  0x8000 firmware/esp32-csi-node/build/partition_table/partition-table.bin \
+  0x10000 firmware/esp32-csi-node/build/esp32-csi-node.bin
+```
+
+## What's Detected
+
+With a single ESP32-S3, you can detect:
+
+| Feature | Description |
+|---------|-------------|
+| **Presence** | Is someone in the room? (Yes/No) |
+| **Motion** | Is someone moving? |
+| **Distance** | Approximate distance from the ESP32 |
+
+## What's NOT Available (Needs 2+ Nodes)
+
+- Full body pose (17 keypoints)
+- Breathing rate
+- Heart rate
+- 3D position tracking
+
+## Troubleshooting
+
+**No data appearing?**
+- Check ESP32 is connected to WiFi: `python -m serial.tools.miniterm COM7 115200`
+- Verify the IP address is reachable from your PC
+- Make sure your WiFi router is on the same network
+
+**Getting errors?**
+- Check the logs in `logs/` folder
+- Verify COM port is correct (check Device Manager on Windows)
+
+## Files in This Demo
+
+```
+demo-single-esp32s3/
+├── README.md           # This file
+├── setup.sh            # Quick setup script
+└── config.env.example  # Example configuration
+```
+
+## License
+
+MIT - Same as main RuView project