perf(build): add fat LTO + single codegen-unit to desktop release profile

The renderer is GPU-bound, but Bevy's CPU path (resource management,
system scheduling, egui, wgpu command submission) still benefits from
cross-crate inlining. Cargo's default release profile skips LTO and
splits codegen across 16 units, leaving inter-crate trampolines through
Bevy/wgpu in the hot path.

- lto = "fat": whole-program cross-crate inlining.
- codegen-units = 1: best optimization (slower compiles, accepted).
- panic = "abort": smaller binary, no unwind tables.
- strip = "symbols": drop debug symbols from the shipped binary.

wasm-release inherits release then overrides opt-level to "z", so web
builds keep their size focus. Release build verified; cargo test green
(14 passed).

Cargo.toml

@@ -17,6 +17,21 @@ web-sys = { version = "0.3", features = ["Gpu", "Navigator", "Window", "Document
 wasm-bindgen = "0.2"
 js-sys = "0.3"
 
+# Desktop release tuning. This renderer is GPU-bound, but Bevy's CPU path
+# (resource management, system scheduling, egui, wgpu command submission)
+# still benefits measurably from cross-crate LTO and a single codegen unit:
+# - lto = "fat": cross-crate inlining, removes trampolines through Bevy/wgpu.
+# - codegen-units = 1: best optimization, at the cost of slower compiles.
+# - panic = "abort": smaller binary, no unwind tables in the hot path.
+# - strip: drop debug symbols from the shipped binary.
+# `wasm-release` inherits release, so web picks these up too (then overrides
+# opt-level to "z" for binary size).
+[profile.release]
+lto = "fat"
+codegen-units = 1
+panic = "abort"
+strip = "symbols"
+
 # Smaller wasm binary in release web builds (per Bevy examples README).
 [profile.wasm-release]
 inherits = "release"