feat: 增加 Agent Skill 工具绑定数据结构

- 新增 Agent 与 Skill 草稿绑定及发布快照字段

- 新增 Skill 工具绑定、冻结摘要与运行配置字段

easyflow-starter/easyflow-starter-all/src/main/resources/db/migration/mysql/V56__mysql_agent_skill_tool_binding.sql

@@ -0,0 +1,65 @@
+SET NAMES utf8mb4;
+
+-- MySQL DDL 不具备整段事务回滚能力，使用存在性守卫保证部分成功后可以安全重跑。
+SET @add_skill_published_tool_bindings = (
+    SELECT IF(COUNT(1) = 0,
+              'ALTER TABLE `tb_skill` ADD COLUMN `published_tool_bindings_json` JSON NULL COMMENT ''已发布平台 Tool 冻结快照'' AFTER `published_snapshot_json`',
+              'SELECT 1')
+    FROM information_schema.columns
+    WHERE table_schema = DATABASE()
+      AND table_name = 'tb_skill'
+      AND column_name = 'published_tool_bindings_json');
+PREPARE add_skill_published_tool_bindings_stmt FROM @add_skill_published_tool_bindings;
+EXECUTE add_skill_published_tool_bindings_stmt;
+DEALLOCATE PREPARE add_skill_published_tool_bindings_stmt;
+
+CREATE TABLE IF NOT EXISTS `tb_skill_tool_binding` (
+    `id` BIGINT NOT NULL COMMENT 'ID',
+    `tenant_id` BIGINT NOT NULL COMMENT '租户ID',
+    `skill_id` BIGINT NOT NULL COMMENT 'Skill ID',
+    `tool_type` VARCHAR(32) NOT NULL COMMENT 'WORKFLOW / PLUGIN / MCP',
+    `target_id` BIGINT NOT NULL COMMENT '目标资源ID',
+    `hitl_enabled` TINYINT(1) NOT NULL DEFAULT 0 COMMENT '是否调用前确认',
+    `mcp_tool_count` INT NULL COMMENT 'MCP Tool 数量',
+    `mcp_tool_manifest_hash` VARCHAR(64) NULL COMMENT 'MCP Tool 清单 hash',
+    `sort_no` INT NOT NULL DEFAULT 0 COMMENT '排序',
+    `created` DATETIME DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
+    `created_by` BIGINT NULL COMMENT '创建人',
+    `modified` DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
+    `modified_by` BIGINT NULL COMMENT '修改人',
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_skill_tool_binding` (`tenant_id`, `skill_id`, `tool_type`, `target_id`),
+    KEY `idx_skill_tool_binding_list` (`tenant_id`, `skill_id`, `sort_no`, `id`),
+    KEY `idx_skill_tool_binding_target` (`tenant_id`, `tool_type`, `target_id`, `skill_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='Skill 平台 Tool 草稿绑定';
+
+CREATE TABLE IF NOT EXISTS `tb_agent_skill_binding` (
+    `id` BIGINT NOT NULL COMMENT 'ID',
+    `tenant_id` BIGINT NOT NULL COMMENT '租户ID',
+    `agent_id` BIGINT NOT NULL COMMENT 'Agent ID',
+    `skill_id` BIGINT NOT NULL COMMENT 'Skill ID',
+    `sort_no` INT NOT NULL DEFAULT 0 COMMENT '排序',
+    `created` DATETIME DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
+    `created_by` BIGINT NULL COMMENT '创建人',
+    `modified` DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改时间',
+    `modified_by` BIGINT NULL COMMENT '修改人',
+    PRIMARY KEY (`id`),
+    UNIQUE KEY `uk_agent_skill_binding` (`tenant_id`, `agent_id`, `skill_id`),
+    KEY `idx_agent_skill_binding_list` (`tenant_id`, `agent_id`, `sort_no`, `id`),
+    KEY `idx_agent_skill_binding_target` (`tenant_id`, `skill_id`, `agent_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='Agent Skill 草稿绑定';
+
+-- 首期统一知识库和 Skill 在菜单与聊天状态中的语义图标。
+UPDATE `tb_sys_menu`
+SET `menu_icon` = 'lucide:book-open-text',
+    `modified` = `modified`,
+    `modified_by` = `modified_by`
+WHERE `id` = 259170422338478080
+  AND `menu_url` = '/ai/documentCollection';
+
+UPDATE `tb_sys_menu`
+SET `menu_icon` = 'lucide:notebook-tabs',
+    `modified` = `modified`,
+    `modified_by` = `modified_by`
+WHERE `id` = 367400000000000001
+  AND `menu_url` = '/ai/skill';