[add]: health endpoint

app/swagger/digifi_swagger.json

@@ -103,6 +103,10 @@
         "description": "Find out more",
         "url": "https://www.simbrellang.net"
       }
+    },
+    {
+      "name": "Health",
+      "description": "System health check including DB status."
     }
   ],
   "paths": {
@@ -138,6 +142,39 @@
     },
     "/transaction-offers": {
       "$ref": "../swagger/paths/TransactionOffers.json"
+    },
+    "/health": {
+      "get": {
+        "tags": ["Health"],
+        "summary": "Health Check",
+        "description": "Returns service health information including DB connection status.",
+        "responses": {
+          "200": {
+            "description": "Health check successful",
+            "content": {
+              "application/json": {
+                "example": {
+                  "status": "ok",
+                  "db_status": "Connection Successful",
+                  "error": []
+                }
+              }
+            }
+          },
+          "500": {
+            "description": "Health check failed",
+            "content": {
+              "application/json": {
+                "example": {
+                  "status": "ok",
+                  "db_status": "Connection Failed",
+                  "error":["could not connect to server: Connection refused"]
+                }
+              }
+            }
+          }
+        }
+      }
     }
   },
   "components": {