learn how workspaces + proc macros work & restructure everything

core/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "iris-core"
+version.workspace = true
+edition.workspace = true
+
+[dependencies]
+winit = { workspace = true }
+wgpu = { workspace = true }
+bytemuck ={ workspace = true }
+image = { workspace = true }
+cosmic-text = { workspace = true }
+fxhash = { workspace = true }
+