feat: Add dynamic host IP detection for Docker Compose and Supabase config

- Add docker-compose.sh wrapper script that auto-detects host IP
- Update docker-compose.yml to use environment variable substitution
- Update Supabase config.toml files to use HOST_SITE_URL and SUPABASE_API_URL env vars
- Add scripts/get-host-ip.sh for IP detection
- Add scripts/set-host-env.sh for environment setup
- Add scripts/supabase-with-env.sh wrapper for Supabase CLI
- Add documentation for Docker Compose environment setup
- Update README.md with new usage instructions
- Replace hardcoded URLs with dynamic environment variables

docs/HOST_IP_CONFIGURATION.md

@@ -0,0 +1,168 @@
+# Host IP Configuration for Supabase
+
+## Overview
+
+The Supabase `config.toml` file uses the `site_url` setting to configure authentication redirects. Instead of hardcoding the host IP address, we now use environment variables that are automatically detected from the host machine.
+
+## Problem
+
+Previously, the `site_url` was hardcoded (e.g., `http://exp-dash:3000`), which:
+- Doesn't work when the host IP changes
+- Requires manual updates for different environments
+- Is not portable across different machines
+
+## Solution
+
+We now use the `HOST_SITE_URL` environment variable, which is automatically detected using the host machine's IP address.
+
+## Usage
+
+### Automatic Detection (Recommended)
+
+Use the provided scripts to automatically detect and set the host IP:
+
+```bash
+# Option 1: Source the environment setup script
+source ./scripts/set-host-env.sh
+
+# Then run Supabase CLI commands normally
+supabase start
+supabase db reset
+```
+
+Or use the wrapper script that does this automatically:
+
+```bash
+# Use the wrapper script for Supabase CLI commands
+./scripts/supabase-with-env.sh start
+./scripts/supabase-with-env.sh db reset
+```
+
+### Manual Configuration
+
+If automatic detection doesn't work or you want to use a specific IP:
+
+```bash
+# Set the environment variable manually
+export HOST_SITE_URL="http://192.168.1.100:3000"
+
+# Or with a different port
+export HOST_SITE_URL="http://192.168.1.100:8080"
+
+# Then run Supabase commands
+supabase start
+```
+
+### For Docker Compose
+
+If you're using Docker Compose and need to set this for Supabase CLI commands run on the host:
+
+```bash
+# Before running docker compose or Supabase CLI
+export HOST_SITE_URL="http://$(./scripts/get-host-ip.sh):3000"
+docker compose up -d
+```
+
+Or add it to your shell profile (`~/.bashrc` or `~/.zshrc`):
+
+```bash
+# Add to ~/.bashrc or ~/.zshrc
+export HOST_SITE_URL="http://$(/path/to/USDA-VISION/scripts/get-host-ip.sh):3000"
+```
+
+## How It Works
+
+1. **IP Detection Script** (`scripts/get-host-ip.sh`):
+   - Tries multiple methods to detect the host IP
+   - Works both inside Docker containers and on the host machine
+   - Falls back to `127.0.0.1` if detection fails
+
+2. **Environment Setup Script** (`scripts/set-host-env.sh`):
+   - Calls the IP detection script
+   - Sets `HOST_SITE_URL` environment variable
+   - Can be sourced to set the variable in your current shell
+
+3. **Supabase Wrapper Script** (`scripts/supabase-with-env.sh`):
+   - Automatically sets `HOST_SITE_URL` before running Supabase CLI
+   - Transparent wrapper - just use it instead of `supabase` command
+
+4. **Config File** (`supabase/config.toml`):
+   - Uses `env(HOST_SITE_URL)` to read the environment variable
+   - Supabase CLI automatically substitutes the value
+
+## Detection Methods
+
+The IP detection script tries these methods in order:
+
+1. **Default Gateway** (for containers): Gets the gateway IP which is typically the host
+2. **host.docker.internal**: Uses Docker's special DNS name (if available)
+3. **Network Interface**: Checks common network interfaces (eth0, enp0s8, etc.)
+4. **Hostname Resolution**: Uses `hostname -I` to get the host IP
+5. **Fallback**: Returns `127.0.0.1` if all methods fail
+
+## Troubleshooting
+
+### IP Detection Fails
+
+If the script can't detect the IP:
+
+1. **Check network interfaces**:
+   ```bash
+   ip addr show
+   # or
+   ifconfig
+   ```
+
+2. **Manually set the IP**:
+   ```bash
+   export HOST_SITE_URL="http://YOUR_ACTUAL_IP:3000"
+   ```
+
+3. **Verify the IP is accessible**:
+   ```bash
+   ping $(./scripts/get-host-ip.sh)
+   ```
+
+### Supabase CLI Doesn't Use the Variable
+
+Make sure you:
+1. Set `HOST_SITE_URL` before running Supabase CLI
+2. Run Supabase CLI from the project root (where `supabase/` directory is)
+3. Check that `config.toml` uses `env(HOST_SITE_URL)` syntax
+
+### Port Mismatch
+
+If your React app runs on a different port, adjust the port in the URL:
+
+```bash
+export HOST_SITE_URL="http://$(./scripts/get-host-ip.sh):8080"
+```
+
+## Example Workflow
+
+```bash
+# 1. Navigate to project root
+cd /path/to/USDA-VISION
+
+# 2. Set the environment variable (automatic detection)
+source ./scripts/set-host-env.sh
+
+# 3. Verify it's set
+echo $HOST_SITE_URL
+# Output: http://192.168.1.100:3000
+
+# 4. Start Supabase
+supabase start
+
+# Or use the wrapper script (does steps 2-4 automatically)
+./scripts/supabase-with-env.sh start
+```
+
+## Integration with Docker Compose
+
+If you're running Supabase via Docker Compose (not CLI), the containers use their own networking. The `HOST_SITE_URL` is primarily for Supabase CLI commands that run on the host machine.
+
+For container-to-container communication, use Docker service names (e.g., `http://web:8080`).
+
+For browser-based redirects from Supabase Auth back to your React app, use the actual host IP that the browser can access.
+