feat: RFCP MVP deployed on VPS

Iteration 1:
- Dark theme with 3-way toggle
- Dynamic heatmap gradient (blue→red)
- Radius up to 100km
- Save & Calculate workflow

Iteration 2:
- Terrain overlay toggle
- Batch height operations
- Zoom-dependent heatmap rendering

Infrastructure:
- Backend FastAPI on 8888
- Frontend static build via Caddy
- Systemd services
- Caddy reverse proxy integration

scripts/download-terrain.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+set -e
+
+TERRAIN_DIR="/opt/rfcp/data/terrain"
+mkdir -p $TERRAIN_DIR
+cd $TERRAIN_DIR
+
+echo "📡 Downloading Ukraine SRTM 30m tiles..."
+
+# CGIAR SRTM (easiest, no auth needed)
+BASE="https://srtm.csi.cgiar.org/wp-content/uploads/files/srtm_5x5/TIFF"
+
+# Download Ukraine tiles
+wget -c $BASE/srtm_39_02.zip
+wget -c $BASE/srtm_40_02.zip
+wget -c $BASE/srtm_41_02.zip
+wget -c $BASE/srtm_39_03.zip
+wget -c $BASE/srtm_40_03.zip
+
+echo "📦 Extracting..."
+for f in *.zip; do
+    unzip -o $f
+    rm $f
+done
+
+echo "✅ Terrain data ready: $(ls *.tif | wc -l) tiles"
+du -sh $TERRAIN_DIR