feat: 按模型上下文自动配置智能体压缩阈值

- 从 llm.json 解析上下文与输出上限，并增强短模型 ID 匹配

- 切换模型、保存和试运行时按预算公式重算，目录缺失时回退 30K

- 修复模型列表接口未返回能力元数据

easyflow-ui-admin/app/src/views/ai/agents/composables/useAgentDesignerState.ts

@@ -9,6 +9,7 @@ import type {
 
 import { computed, reactive } from 'vue';
 
+import { DEFAULT_AGENT_COMPRESSION_TOKEN_THRESHOLD } from '../compression-threshold';
 import {
   buildInteractionConfigPayload,
   createEmptyInteractionConfig,
@@ -103,7 +104,7 @@ export function createEmptyAgent(): AgentInfo {
       compressionParameter: {
         enabled: true,
         lastKeep: 8,
-        minCompressionTokenThreshold: 6000,
+        minCompressionTokenThreshold: DEFAULT_AGENT_COMPRESSION_TOKEN_THRESHOLD,
       },
     },
     interactionConfigJson: createEmptyInteractionConfig(),