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/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "devflow"
+version = "0.1.0"
+description = "DevFlow Desktop App"
+authors = [""]
+edition = "2021"
+
+[lib]
+name = "devflow_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+tauri = { version = "2", features = [] }
+tauri-plugin-opener = "2"
+serde.workspace = true
+serde_json.workspace = true
+tokio.workspace = true
+anyhow.workspace = true
+tracing.workspace = true
+
+# 后端 crate
+df-core = { path = "../crates/df-core" }
+df-storage = { path = "../crates/df-storage" }
+df-workflow = { path = "../crates/df-workflow" }
+df-nodes = { path = "../crates/df-nodes" }
+df-execute = { path = "../crates/df-execute" }
+df-ai = { path = "../crates/df-ai" }
+futures = "0.3"