feat: complete MongoDB to CouchDB migration

- Migrate Report model to CouchDB with embedded street/user data
- Migrate UserBadge model to CouchDB with badge population
- Update all remaining routes (reports, users, badges, payments) to use CouchDB
- Add CouchDB health check and graceful shutdown to server.js
- Add missing methods to couchdbService (checkConnection, findWithPagination, etc.)
- Update Kubernetes deployment manifests for CouchDB support
- Add comprehensive CouchDB setup documentation

All core functionality now uses CouchDB as primary database while maintaining
MongoDB for backward compatibility during transition period.

🤖 Generated with [AI Assistant]

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

backend/server.js

@@ -72,7 +72,10 @@ mongoose
 // CouchDB (primary database)
 couchdbService.initialize()
   .then(() => console.log("CouchDB initialized"))
-  .catch((err) => console.log("CouchDB initialization error:", err));
+  .catch((err) => {
+    console.log("CouchDB initialization error:", err);
+    process.exit(1); // Exit if CouchDB fails to initialize since it's the primary database
+  });
 
 // Socket.IO Authentication Middleware
 io.use(socketAuth);
@@ -123,13 +126,27 @@ app.use("/api/auth/login", authLimiter);
 app.use("/api", apiLimiter);
 
 // Health check endpoint (for Kubernetes liveness/readiness probes)
-app.get("/api/health", (req, res) => {
-  res.status(200).json({
-    status: "healthy",
-    timestamp: new Date().toISOString(),
-    uptime: process.uptime(),
-    mongodb: mongoose.connection.readyState === 1 ? "connected" : "disconnected",
-  });
+app.get("/api/health", async (req, res) => {
+  try {
+    const couchdbStatus = await couchdbService.checkConnection();
+    
+    res.status(200).json({
+      status: "healthy",
+      timestamp: new Date().toISOString(),
+      uptime: process.uptime(),
+      mongodb: mongoose.connection.readyState === 1 ? "connected" : "disconnected",
+      couchdb: couchdbStatus ? "connected" : "disconnected",
+    });
+  } catch (error) {
+    res.status(503).json({
+      status: "unhealthy",
+      timestamp: new Date().toISOString(),
+      uptime: process.uptime(),
+      mongodb: mongoose.connection.readyState === 1 ? "connected" : "disconnected",
+      couchdb: "disconnected",
+      error: error.message,
+    });
+  }
 });
 
 // Routes
@@ -156,3 +173,42 @@ app.use(errorHandler);
 server.listen(port, () => {
   console.log(`Server running on port ${port}`);
 });
+
+// Graceful shutdown
+process.on("SIGTERM", async () => {
+  console.log("SIGTERM received, shutting down gracefully");
+  
+  try {
+    // Close MongoDB connection
+    await mongoose.connection.close();
+    console.log("MongoDB connection closed");
+    
+    // Close server
+    server.close(() => {
+      console.log("Server closed");
+      process.exit(0);
+    });
+  } catch (error) {
+    console.error("Error during shutdown:", error);
+    process.exit(1);
+  }
+});
+
+process.on("SIGINT", async () => {
+  console.log("SIGINT received, shutting down gracefully");
+  
+  try {
+    // Close MongoDB connection
+    await mongoose.connection.close();
+    console.log("MongoDB connection closed");
+    
+    // Close server
+    server.close(() => {
+      console.log("Server closed");
+      process.exit(0);
+    });
+  } catch (error) {
+    console.error("Error during shutdown:", error);
+    process.exit(1);
+  }
+});