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

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -0,0 +1,19 @@
+name: 🚀 Feature Request
+description: Suggest an idea, feature, or enhancement
+title: "[FEATURE]:"
+
+body:
+  - type: checkboxes
+    id: verified
+    attributes:
+      label: Feature hasn't been suggested before.
+      options:
+        - label: I have verified this feature I'm about to request hasn't been suggested before.
+          required: true
+
+  - type: textarea
+    attributes:
+      label: Describe the enhancement you want to request
+      description: What do you want to change or add? What are the benefits of implementing this? Try to be detailed so we can understand your request better :)
+    validations:
+      required: true