fix: memory scope_id column overflow and API read mismatch

AgentRuntime writes scope_id as {user_id}:{agent_id} (73 chars) but:
- DB columns were CHAR(36)/VARCHAR(36), causing Data too long errors
- Memory API queried with agent_id only, returning empty results

- Add _mem_scope() helper to build correct scope_id format
- Update all CRUD queries in agent_memory.py to use _mem_scope()
- Enhance login failure logging in auth.py

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

android/app/src/main/java/com/tiangong/aiagent/ui/login/LoginScreen.kt

@@ -75,6 +75,39 @@ fun LoginScreen(
 
             // Server URL
             if (isEditingUrl) {
+                // Preset quick-select buttons
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.spacedBy(8.dp)
+                ) {
+                    val isLocalSelected = editedUrl == "http://192.168.31.135:8037"
+                    val isCloudSelected = editedUrl == "http://101.43.95.130:8037"
+                    OutlinedButton(
+                        onClick = { editedUrl = "http://192.168.31.135:8037" },
+                        colors = if (isLocalSelected) {
+                            ButtonDefaults.outlinedButtonColors(
+                                containerColor = MaterialTheme.colorScheme.primaryContainer
+                            )
+                        } else {
+                            ButtonDefaults.outlinedButtonColors()
+                        }
+                    ) {
+                        Text("本地")
+                    }
+                    OutlinedButton(
+                        onClick = { editedUrl = "http://101.43.95.130:8037" },
+                        colors = if (isCloudSelected) {
+                            ButtonDefaults.outlinedButtonColors(
+                                containerColor = MaterialTheme.colorScheme.primaryContainer
+                            )
+                        } else {
+                            ButtonDefaults.outlinedButtonColors()
+                        }
+                    ) {
+                        Text("云服务")
+                    }
+                }
+                Spacer(modifier = Modifier.height(8.dp))
                 OutlinedTextField(
                     value = editedUrl,
                     onValueChange = { editedUrl = it },
@@ -84,7 +117,7 @@ fun LoginScreen(
                     modifier = Modifier.fillMaxWidth(),
                     keyboardOptions = KeyboardOptions(imeAction = ImeAction.Next),
                     enabled = !uiState.isLoading,
-                    supportingText = { Text("输入后点击保存，设置即时生效") }
+                    supportingText = { Text("点击上方快捷选择，或手动输入后保存") }
                 )
                 Row(
                     modifier = Modifier.fillMaxWidth(),