✨♻️ bevy_vanth, vanth, vanth_derive, flake: Add Bevy integration crate and refactor entity/networking

- Created new crate `bevy_vanth` with basic plugin structure for Bevy integration.
- Refactored `Id` generation in `vanth` to use `OsRng` and removed redundant `to_u128_pair`/`from_u128_pair` methods.
- Moved networking functionality into new `net` module with `Node`, `Packet`, and `Message` types.
- Updated `vanth_derive` to use `proc-macro-crate` for reliable crate path resolution.
- Added `rand` dependency to replace custom ID generation logic.
- Updated `Cargo.toml`/`Cargo.lock` with new dependencies: `bevy_app`, `nix`, `cfg_aliases`, `proc-macro-crate`.
- Modified `README.md` with improved project description.
- Added commented clippy check in `flake.nix`.

crates/bevy_vanth/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "bevy_vanth"
+version.workspace = true
+edition.workspace = true
+
+[dependencies]
+bevy_ecs.workspace = true
+bevy_app.workspace = true

crates/bevy_vanth/src/lib.rs

@@ -0,0 +1,20 @@
+use bevy_app::Plugin;
+use bevy_ecs::component::Component;
+
+#[derive(Component)]
+pub struct VanthRoot {}
+
+pub struct VanthPlugin {}
+
+impl Plugin for VanthPlugin {
+    fn build(&self, app: &mut bevy_app::App) {
+        // TODO: Allow specifying custom schedules.
+        app.add_systems(bevy_app::FixedPreUpdate, run_vanth).finish();
+    }
+}
+
+impl VanthPlugin {}
+
+fn run_vanth() {
+    
+}