chore(repo): 完善仓库维护与自动化 (#108)

统一 Node.js 24 LTS、CI、文档和发布工作流配置。

完善仓库维护规范、Dependabot 与贡献文档，清理生成产物并统一既有 Go 代码格式。

.github/dependabot.yml

@@ -0,0 +1,86 @@
+version: 2
+
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+      day: monday
+      time: "03:00"
+      timezone: Asia/Shanghai
+    open-pull-requests-limit: 5
+    commit-message:
+      prefix: chore(deps)
+    groups:
+      github-actions:
+        patterns:
+          - "*"
+
+  - package-ecosystem: gomod
+    directory: /server
+    schedule:
+      interval: weekly
+      day: monday
+      time: "03:10"
+      timezone: Asia/Shanghai
+    open-pull-requests-limit: 5
+    commit-message:
+      prefix: chore(deps)
+    groups:
+      go-minor-and-patch:
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch
+
+  - package-ecosystem: npm
+    directory: /web
+    schedule:
+      interval: weekly
+      day: monday
+      time: "03:20"
+      timezone: Asia/Shanghai
+    open-pull-requests-limit: 5
+    commit-message:
+      prefix: chore(deps)
+    groups:
+      web-minor-and-patch:
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch
+
+  - package-ecosystem: npm
+    directory: /docs-site
+    schedule:
+      interval: weekly
+      day: monday
+      time: "03:30"
+      timezone: Asia/Shanghai
+    open-pull-requests-limit: 5
+    commit-message:
+      prefix: chore(deps)
+    groups:
+      docs-minor-and-patch:
+        patterns:
+          - "*"
+        update-types:
+          - minor
+          - patch
+
+  - package-ecosystem: docker
+    directory: /
+    schedule:
+      interval: weekly
+      day: monday
+      time: "03:40"
+      timezone: Asia/Shanghai
+    open-pull-requests-limit: 5
+    commit-message:
+      prefix: chore(deps)
+    groups:
+      container-images:
+        patterns:
+          - "*"