feat: initialize cargo workspace with voltex_math, voltex_platform, voltex_renderer

Phase 1 Task 1 - workspace scaffolding with stub crates

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/triangle/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "triangle"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+voltex_math.workspace = true
+voltex_platform.workspace = true
+voltex_renderer.workspace = true
+wgpu.workspace = true
+winit.workspace = true
+bytemuck.workspace = true
+pollster.workspace = true
+env_logger.workspace = true
+log.workspace = true

examples/triangle/src/main.rs

@@ -0,0 +1,4 @@
+// examples/triangle/src/main.rs
+fn main() {
+    println!("Voltex Triangle Demo");
+}