chore: scaffold Tauri 2 + Svelte 5 workspace

Standard Tauri layout with a Svelte 5 + TypeScript + Vite frontend and a
Rust backend in src-tauri. Adds build tooling, app/window config,
capabilities, generated icons and the project README.

src-tauri/Cargo.toml

@@ -0,0 +1,53 @@
+[package]
+name = "mermix"
+version = "0.1.0"
+description = "Cross-platform Mermaid editor & viewer with Git-backed projects"
+authors = ["Mermix"]
+edition = "2021"
+rust-version = "1.77"
+
+[lib]
+# The `_lib` suffix keeps the library name distinct from the binary so the
+# Tauri mobile bindings can link against it.
+name = "mermix_lib"
+crate-type = ["staticlib", "cdylib", "rlib"]
+
+[build-dependencies]
+tauri-build = { version = "2", features = [] }
+
+[dependencies]
+tauri = { version = "2", features = [] }
+tauri-plugin-dialog = "2"
+
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+# App-level metadata store (project registry + settings).
+sqlx = { version = "0.8", default-features = false, features = [
+    "runtime-tokio",
+    "sqlite",
+    "chrono",
+    "macros",
+] }
+
+# Per-project version control.
+git2 = "0.19"
+
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "fs", "sync"] }
+thiserror = "1"
+chrono = { version = "0.4", features = ["serde"] }
+uuid = { version = "1", features = ["v4", "serde"] }
+directories = "5"
+toml = "0.8"
+
+[features]
+# This feature is used for production builds or when a dev server is not
+# specified, DO NOT REMOVE!!
+custom-protocol = ["tauri/custom-protocol"]
+
+[profile.release]
+panic = "abort"
+codegen-units = 1
+lto = true
+opt-level = "s"
+strip = true