Vendor Bevy rendering crates (Phase 1 complete)

Closes #6, #7, #8, #9, #10
Refs #2, #122

Vendored bevy_render, bevy_core_pipeline, and bevy_pbr from Bevy v0.17.2
(commit 566358363126dd69f6e457e47f306c68f8041d2a) into libmarathon.

- ~51K LOC vendored to crates/libmarathon/src/render/
- Merged bevy_render_macros into crates/macros/
- Fixed 773→0 compilation errors
- Updated dependencies (encase 0.10→0.11, added 4 new deps)
- Removed bevy_render/pbr/core_pipeline from app Cargo features

All builds passing, macOS smoke test successful.

Signed-off-by: Sienna Meridian Satterwhite <sienna@r3t.io>

crates/app/Cargo.toml

@@ -12,9 +12,7 @@ headless = []
 [dependencies]
 libmarathon = { path = "../libmarathon" }
 bevy = { version = "0.17", default-features = false, features = [
-    "bevy_render",
-    "bevy_core_pipeline",
-    "bevy_pbr",
+    # bevy_render, bevy_core_pipeline, bevy_pbr are now vendored in libmarathon
     "bevy_ui",
     "bevy_text",
     "png",