Fix container networking: Use container IP for health checks

Root Cause Identified:
- Gitea runner runs inside docker.gitea.com/runner-images:ubuntu-latest
- App container runs as sibling container, not accessible via localhost:8080
- Port mapping works for host access, but not container-to-container

 Networking Solution:
- Get container IP with: docker inspect ping-river-monitor-test
- Connect directly to container IP:8000 (internal port)
- Fallback to localhost:8080 if IP detection fails
- Bypasses localhost networking issues in containerized CI

 Updated Health Checks:
- Use container IP for direct communication
- Test internal port 8000 instead of mapped port 8080
- More reliable in containerized CI environments
- Better debugging with container IP logging

 Should resolve curl connection failures in Gitea CI environment

.gitea/workflows/release.yml

@@ -223,11 +223,21 @@ jobs:
           for i in {1..15}; do
             echo "⏳ Attempt $i/15: Testing health endpoint..."
             
-            # Test health endpoint with detailed debugging
+            # Test health endpoint with container networking
             echo "Testing health endpoint..."
             
-            # First try with verbose output to see what's happening
-            response=$(curl -s --max-time 10 --connect-timeout 5 -w "HTTP_CODE:%{http_code}" http://127.0.0.1:8080/health)
+            # Get the container's IP address for direct communication
+            CONTAINER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' ping-river-monitor-test)
+            echo "Container IP: $CONTAINER_IP"
+            
+            # Test using container IP directly (port 8000 inside container)
+            if [ -n "$CONTAINER_IP" ]; then
+              response=$(curl -s --max-time 10 --connect-timeout 5 -w "HTTP_CODE:%{http_code}" http://$CONTAINER_IP:8000/health)
+            else
+              # Fallback to localhost if IP detection fails
+              response=$(curl -s --max-time 10 --connect-timeout 5 -w "HTTP_CODE:%{http_code}" http://127.0.0.1:8080/health)
+            fi
+            
             http_code=$(echo "$response" | grep -o "HTTP_CODE:[0-9]*" | cut -d: -f2)
             response_body=$(echo "$response" | sed 's/HTTP_CODE:[0-9]*$//')
             
@@ -248,13 +258,24 @@ jobs:
             fi
           done
 
-          # Test API endpoints with better error handling
+          # Test API endpoints with container networking
           echo "🧪 Testing API endpoints..."
           
+          # Get container IP for direct communication
+          CONTAINER_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' ping-river-monitor-test)
+          echo "Using container IP: $CONTAINER_IP"
+          
           endpoints=("health" "docs" "stations" "metrics")
           for endpoint in "${endpoints[@]}"; do
             echo "Testing /$endpoint..."
-            response=$(curl -s --max-time 10 -w "HTTP_CODE:%{http_code}" http://127.0.0.1:8080/$endpoint)
+            
+            # Use container IP if available, otherwise fallback to localhost
+            if [ -n "$CONTAINER_IP" ]; then
+              response=$(curl -s --max-time 10 -w "HTTP_CODE:%{http_code}" http://$CONTAINER_IP:8000/$endpoint)
+            else
+              response=$(curl -s --max-time 10 -w "HTTP_CODE:%{http_code}" http://127.0.0.1:8080/$endpoint)
+            fi
+            
             http_code=$(echo "$response" | grep -o "HTTP_CODE:[0-9]*" | cut -d: -f2)
             
             if [ "$http_code" = "200" ]; then