Implement container logs handler

- Add Docker client to handlers for container operations
- Implement HandleAppLogs() to fetch and return container logs
- Support ?tail=N query parameter (default 500 lines)
- Handle missing container gracefully

internal/handlers/app.go

@@ -331,6 +331,9 @@ func (h *Handlers) HandleAppDeployments() http.HandlerFunc {
 	}
 }
 
+// defaultLogTail is the default number of log lines to fetch.
+const defaultLogTail = "500"
+
 // HandleAppLogs returns the container logs handler.
 func (h *Handlers) HandleAppLogs() http.HandlerFunc {
 	return func(writer http.ResponseWriter, request *http.Request) {
@@ -343,16 +346,37 @@ func (h *Handlers) HandleAppLogs() http.HandlerFunc {
 			return
 		}
 
-		// Container logs fetching not yet implemented
-		writer.Header().Set("Content-Type", "text/plain")
+		writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
 
 		if !application.ContainerID.Valid {
-			_, _ = writer.Write([]byte("No container running"))
+			_, _ = writer.Write([]byte("No container running\n"))
 
 			return
 		}
 
-		_, _ = writer.Write([]byte("Container logs not implemented yet"))
+		tail := request.URL.Query().Get("tail")
+		if tail == "" {
+			tail = defaultLogTail
+		}
+
+		logs, logsErr := h.docker.ContainerLogs(
+			request.Context(),
+			application.ContainerID.String,
+			tail,
+		)
+		if logsErr != nil {
+			h.log.Error("failed to get container logs",
+				"error", logsErr,
+				"app", application.Name,
+				"container", application.ContainerID.String,
+			)
+
+			_, _ = writer.Write([]byte("Failed to fetch container logs\n"))
+
+			return
+		}
+
+		_, _ = writer.Write([]byte(logs))
 	}
 }