feat: 足迹 Footprints 个人留痕系统

桌面应用(Tauri+React+SQLite)：时间线/记录/学年学科成绩梯度/统计/类型与字段模板/附件内容寻址/详情视图/PWA

同步服务端(sync-server)：多用户+邀请码/LWW推拉/seq游标/附件去重/Docker部署

多端同步地基：uuid v7/HLC混合逻辑时钟/软删除墓碑/sync_oplog，Node与Rust双端一致并通过自动化测试

app/src-tauri/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "footprints"
+version = "0.1.0"
+description = "个人留痕系统 Footprints"
+edition = "2021"
+
+[lib]
+name = "footprints_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+tauri = { version = "2", features = [] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+rusqlite = { version = "0.32", features = ["bundled"] }
+base64 = "0.22"
+uuid = { version = "1", features = ["v7"] }
+sha2 = "0.10"