chore: 初始化 BlockFlow Workbench 仓库

建立前端与 Tauri 桌面端的首个版本提交，包含核心编辑器、项目文件读写、测试与构建配置。

补充 Git 忽略规则和换行规范，排除依赖、构建产物、本地运行日志与临时验证文件，方便在其他电脑继续开发。

src-tauri/capabilities/default.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "../gen/schemas/desktop-schema.json",
+  "identifier": "default",
+  "description": "Permissions for the BlockFlow Workbench desktop window.",
+  "windows": ["main"],
+  "permissions": [
+    "core:default",
+    "dialog:default",
+    "dialog:allow-open",
+    "fs:default",
+    "fs:allow-exists",
+    "fs:allow-lstat",
+    "fs:allow-mkdir",
+    "fs:allow-read-dir",
+    "fs:allow-read-text-file",
+    "fs:allow-write-text-file"
+  ]
+}