Add STEGASOO_PORT env var, improve RPi setup output, channel key accordion

- Add STEGASOO_PORT environment variable support (default: 5000)
- Update .env.example with port and fix channel key format docs
- Move channel key generation to collapsible accordion in Generate page
- Improve RPi setup.sh output with HTTPS and channel key instructions
- Add rpi/BUILD_IMAGE.md workflow documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

rpi/BUILD_IMAGE.md

@@ -0,0 +1,108 @@
+# Stegasoo Pi Image Build Workflow
+
+Quick reference for building a distributable SD card image.
+
+## Step 1: Flash Fresh Raspbian
+
+Use rpi-imager with these settings:
+- **OS**: Raspberry Pi OS (64-bit)
+- **Hostname**: `stegasoo`
+- **Enable SSH**: Yes (password auth)
+- **Username**: `pi` (or any)
+- **Password**: `raspberry` (temporary)
+- **WiFi**: Skip (use ethernet for clean image)
+
+## Step 2: Boot & SSH In
+
+```bash
+# Wait for Pi to boot (~60 seconds), then:
+ssh pi@stegasoo.local
+# or use IP from router DHCP list
+```
+
+## Step 3: Run Setup Script
+
+```bash
+curl -sSL https://raw.githubusercontent.com/adlee-was-taken/stegasoo/main/rpi/setup.sh | bash
+```
+
+This takes ~15-20 minutes and installs:
+- Python 3.12 via pyenv
+- jpegio (patched for ARM)
+- Stegasoo with web UI
+- Systemd service
+
+## Step 4: Test It Works
+
+```bash
+sudo systemctl start stegasoo
+curl -k https://localhost:5000
+# Should return HTML
+```
+
+## Step 5: Sanitize for Distribution
+
+```bash
+curl -sSL https://raw.githubusercontent.com/adlee-was-taken/stegasoo/main/rpi/sanitize-for-image.sh | sudo bash
+```
+
+This removes:
+- WiFi credentials
+- SSH authorized keys
+- Bash history
+- Stegasoo auth database
+- Logs and temp files
+
+The Pi will shut down when complete.
+
+## Step 6: Copy the Image
+
+Remove SD card, insert into your Linux machine:
+
+```bash
+# Find the SD card device (CAREFUL!)
+lsblk
+
+# Copy (replace sdX with actual device, e.g., sda)
+sudo dd if=/dev/sdX of=stegasoo-rpi-$(date +%Y%m%d).img bs=4M status=progress
+```
+
+## Step 7: Shrink & Compress
+
+```bash
+# Optional: Shrink image (saves space)
+wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
+chmod +x pishrink.sh
+sudo ./pishrink.sh stegasoo-rpi-*.img
+
+# Compress
+xz -9 -T0 stegasoo-rpi-*.img
+```
+
+## Step 8: Distribute
+
+Upload `.img.xz` to GitHub Releases.
+
+Users can flash with:
+```bash
+# Linux
+xzcat stegasoo-rpi-*.img.xz | sudo dd of=/dev/sdX bs=4M status=progress
+
+# Or use rpi-imager "Use custom" option
+```
+
+---
+
+## Quick Command Summary
+
+```bash
+# On Pi:
+curl -sSL https://raw.githubusercontent.com/adlee-was-taken/stegasoo/main/rpi/setup.sh | bash
+sudo systemctl start stegasoo
+curl -k https://localhost:5000
+curl -sSL https://raw.githubusercontent.com/adlee-was-taken/stegasoo/main/rpi/sanitize-for-image.sh | sudo bash
+
+# On your machine:
+sudo dd if=/dev/sdX of=stegasoo-rpi-$(date +%Y%m%d).img bs=4M status=progress
+xz -9 -T0 stegasoo-rpi-*.img
+```

rpi/setup.sh

@@ -182,6 +182,7 @@ WorkingDirectory=$INSTALL_DIR/frontends/web
 Environment="PATH=$INSTALL_DIR/venv/bin:/usr/bin"
 Environment="STEGASOO_AUTH_ENABLED=true"
 Environment="STEGASOO_HTTPS_ENABLED=false"
+Environment="STEGASOO_PORT=5000"
 ExecStart=$INSTALL_DIR/venv/bin/python app.py
 Restart=on-failure
 RestartSec=5
@@ -217,8 +218,28 @@ echo "  journalctl -u stegasoo -f"
 echo ""
 echo -e "${GREEN}Access Web UI:${NC}"
 PI_IP=$(hostname -I | awk '{print $1}')
-echo "  http://$PI_IP:5000"
+echo "  http://$PI_IP:5000  (default port, configurable via STEGASOO_PORT)"
 echo ""
 echo -e "${YELLOW}Note: On first access, you'll be prompted to create an admin account.${NC}"
 echo ""
+echo -e "${GREEN}Enable HTTPS:${NC}"
+echo "  sudo nano /etc/systemd/system/stegasoo.service"
+echo ""
+echo "  Change: Environment=\"STEGASOO_HTTPS_ENABLED=false\""
+echo "  To:     Environment=\"STEGASOO_HTTPS_ENABLED=true\""
+echo ""
+echo "  Save (Ctrl+O, Enter, Ctrl+X), then:"
+echo "    sudo systemctl daemon-reload"
+echo "    sudo systemctl restart stegasoo"
+echo ""
+echo -e "${GREEN}Private Channel Key (optional):${NC}"
+echo "  Generate a key:"
+echo "    source $INSTALL_DIR/venv/bin/activate"
+echo "    stegasoo generate --channel-key"
+echo ""
+echo "  Add to the service file (same nano command above):"
+echo "    Environment=\"STEGASOO_CHANNEL_KEY=XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX\""
+echo ""
+echo "  This ensures only users with the same key can decode your images."
+echo ""
 echo -e "To start now: ${YELLOW}sudo systemctl start stegasoo${NC}"