feat: 品牌替换 + 启动优化 + AGENTS.md 模板定制

- 品牌替换：OpenCode/opencode → AirCoding/aircoding（16+ 文件）
- Logo ASCII art：修复 left/right 行数不匹配导致的启动崩溃
- 启动诊断：添加 OPENCODE_PRINT_TIMING 计时探针
- dev 模式默认 --pure 跳过外部插件加载
- AGENTS.md 模板：追加 AirCoding 多 Agent 专项段落
- architect prompt + plugin：强化 AGENTS.md 产出验证

packages/core/migration/20260427172553_slow_nightmare/migration.sql

@@ -0,0 +1,17 @@
+CREATE TABLE `session_message` (
+	`id` text PRIMARY KEY,
+	`session_id` text NOT NULL,
+	`type` text NOT NULL,
+	`time_created` integer NOT NULL,
+	`time_updated` integer NOT NULL,
+	`data` text NOT NULL,
+	CONSTRAINT `fk_session_message_session_id_session_id_fk` FOREIGN KEY (`session_id`) REFERENCES `session`(`id`) ON DELETE CASCADE
+);
+--> statement-breakpoint
+DROP INDEX IF EXISTS `session_entry_session_idx`;--> statement-breakpoint
+DROP INDEX IF EXISTS `session_entry_session_type_idx`;--> statement-breakpoint
+DROP INDEX IF EXISTS `session_entry_time_created_idx`;--> statement-breakpoint
+CREATE INDEX `session_message_session_idx` ON `session_message` (`session_id`);--> statement-breakpoint
+CREATE INDEX `session_message_session_type_idx` ON `session_message` (`session_id`,`type`);--> statement-breakpoint
+CREATE INDEX `session_message_time_created_idx` ON `session_message` (`time_created`);--> statement-breakpoint
+DROP TABLE `session_entry`;