✨➖📝 cli, vanth, meta, flake: Simplify dependencies, add meta crate, and improve docs

- Removed dependencies `sqlx` and `bevy_app` to simplify the project.
- Added new crate `vanth_meta` for generating example SVGs.
- Updated CLI tests to use `assert_cmd` for better test assertions.
- Enhanced README with comprehensive library and CLI usage documentation.
- Modified `Store::write` in `vanth` crate to return the content hash.
- Set `checkPhase` to empty in Nix flake configuration.

crates/meta/src/main.rs

@@ -0,0 +1,181 @@
+//!
+
+use std::f32::consts::PI;
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+struct Point {
+    x: f32,
+    y: f32,
+}
+
+impl Point {
+    fn add_axis_1(&self, amount: f32) -> Self {
+        let angle = 4.0 / 6.0 * PI;
+        (self.x + amount * angle.cos(), self.y + amount * angle.sin()).into()
+    }
+
+    fn add_axis_2(&self, amount: f32) -> Self {
+        let angle = 2.0 / 6.0 * PI;
+        (self.x + amount * angle.cos(), self.y + amount * angle.sin()).into()
+    }
+
+    fn to_string(&self) -> String {
+        format!("{},{}", self.x, self.y)
+    }
+}
+
+impl std::ops::Add for Point {
+    type Output = Self;
+    fn add(self, rhs: Self) -> Self::Output {
+        Point {
+            x: self.x + rhs.x,
+            y: self.y + rhs.y,
+        }
+    }
+}
+
+impl std::ops::AddAssign for Point {
+    fn add_assign(&mut self, rhs: Self) {
+        self.x += rhs.x;
+        self.y += rhs.y;
+    }
+}
+
+impl std::ops::Sub for Point {
+    type Output = Self;
+    fn sub(self, rhs: Self) -> Self::Output {
+        Point {
+            x: self.x - rhs.x,
+            y: self.y - rhs.y,
+        }
+    }
+}
+
+impl std::ops::Mul<f32> for Point {
+    type Output = Self;
+    fn mul(self, rhs: f32) -> Self::Output {
+        Point {
+            x: self.x * rhs,
+            y: self.y * rhs,
+        }
+    }
+}
+
+impl std::ops::Div<f32> for Point {
+    type Output = Self;
+    fn div(self, rhs: f32) -> Self::Output {
+        Point {
+            x: self.x / rhs,
+            y: self.y / rhs,
+        }
+    }
+}
+
+impl std::ops::Neg for Point {
+    type Output = Self;
+    fn neg(self) -> Self::Output {
+        Point { x: -self.x, y: -self.y }
+    }
+}
+
+impl From<(f32, f32)> for Point {
+    fn from((x, y): (f32, f32)) -> Self {
+        Point { x, y }
+    }
+}
+
+impl From<Point> for (f32, f32) {
+    fn from(pt: Point) -> Self {
+        (pt.x, pt.y)
+    }
+}
+
+fn axonometric(x: f32, y: f32) -> Point {
+    let dx = (2.0 / 6.0 * PI).cos();
+    let dy = (2.0 / 6.0 * PI).sin();
+    (50.0 + x * dx + y * dy, 50.0 + x * -dy + y * dx).into()
+}
+
+fn main() {
+    let axis_1_dx = (2.0 / 6.0 * PI).cos();
+    let axis_1_dy = (2.0 / 6.0 * PI).sin();
+    let axis_2_dx = (4.0 / 6.0 * PI).cos();
+    let axis_2_dy = (4.0 / 6.0 * PI).sin();
+
+    // let mut point: Point = (20.0, 20.0).into();
+    // let mut poly_1 = vec![point];
+    // for &diff in &[
+    //     (axis_1_dx * 10.0, axis_1_dy * 10.0),
+    //     (10.0, 0.0),
+    //     (axis_1_dx * -10.0, axis_1_dy * -10.0),
+    // ] {
+    //     point += <_ as Into<Point>>::into(diff);
+    //     poly_1.push(point);
+    // }
+
+    // let mut point: Point = (20.0 + axis_1_dx * 60.0, 20.0).into();
+    // let mut poly_2 = vec![point];
+    // for &diff in &[
+    //     (axis_2_dx * 10.0, axis_2_dy * 10.0),
+    //     (10.0, 0.0),
+    //     (axis_2_dx * -10.0, axis_2_dy * -10.0),
+    // ] {
+    //     point += <_ as Into<Point>>::into(diff);
+    //     poly_2.push(point);
+    // }
+
+    // let mut point: Point = (23.0 + axis_1_dx * 3.0, 20.0 + axis_1_dy * 3.0).into();
+    // let mut poly_3 = vec![point];
+    // for &diff in &[
+    //     (axis_1_dx * 30.0, axis_1_dy * 30.0),
+    //     (axis_2_dx * -30.0, axis_2_dy * -30.0),
+    //     (-10.0, 0.0),
+    //     (axis_2_dx * 10.0, axis_2_dy * 10.0),
+    //     (axis_1_dx * -10.0, axis_1_dy * -10.0),
+    // ] {
+    //     point += <_ as Into<Point>>::into(diff);
+    //     poly_3.push(point);
+    // }
+
+    // let mut poly_4 = vec![
+    //     (20.0 + axis_1_dx * 25.0, 20.0 + axis_1_dy * 25.0).into(),
+    //     (50.0 - axis_2_dx * 25.0, 20.0 + axis_1_dy * 25.0).into(),
+    //     (20.0 + axis_1_dx * 25.0, 25.0 + axis_1_dy * 25.0).into(),
+    // ];
+    
+    let poly_1 = vec![
+        axonometric(10.0, 10.0),
+        axonometric(10.0, 20.0),
+        axonometric(20.0, 20.0),
+    ];
+    
+    let poly_2 = vec![];
+    
+    let poly_3 = vec![];
+    
+    let poly_4 = vec![];
+
+    let mut svg = String::new();
+
+    svg.push_str(
+        r##"<?xml version="1.0" encoding="UTF-8"?>
+        <svg xmlns="http://www.w3.org/2000/svg" width="500" height="500" viewBox="0 0 128 128">
+        <rect width="128" height="128" fill="#ffffff"/>
+        "##,
+    );
+
+    let blue = "#0b5cff";
+    let black = "#000000";
+
+    for (color, points) in &[(blue, poly_1), (blue, poly_2), (blue, poly_4), (black, poly_3)] {
+        svg.push_str(&format!(r##"<g fill="{}">"##, color));
+        svg.push_str(r##"<polygon points=""##);
+        svg.push_str(&points.iter().map(Point::to_string).collect::<Vec<_>>().join(" "));
+        svg.push_str(r##""/>"##);
+        svg.push_str(r##"</g>"##);
+    }
+
+    svg.push_str(r##"</svg>"##);
+
+    println!("{}", svg);
+}