新增: 初始化 DevFlow 项目仓库

Tauri 2 + Vue 3 + Vite 6 桌面应用，Rust workspace 含 13 个 crate
(df-ai / df-storage / df-workflow / df-core / df-execute 等)。
核心能力：AI 聊天 agentic 循环(工具调用+人工审批)、工作流引擎、
任务/想法/项目/阶段管理、可追溯性，及配套前端组件。

src-tauri/capabilities/default.json

@@ -0,0 +1,20 @@
+{
+  "identifier": "default",
+  "description": "DevFlow default permissions",
+  "windows": ["main", "ai-detached"],
+  "permissions": [
+    "core:default",
+    "core:event:default",
+    "core:event:allow-listen",
+    "core:event:allow-emit",
+    "core:window:allow-create",
+    "core:window:allow-close",
+    "core:window:allow-set-always-on-top",
+    "core:window:allow-set-focus",
+    "core:window:allow-set-position",
+    "core:window:allow-set-size",
+    "core:window:allow-outer-position",
+    "core:window:allow-inner-size",
+    "core:webview:allow-create-webview-window"
+  ]
+}