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/macros/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "macros"
+version = "0.1.0"
+edition.workspace = true
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = { version = "2.0", features = ["full"] }
+quote = "1.0"
+proc-macro2 = "1.0"
+inventory = { workspace = true }
+bytes = "1.0"
+bevy_macro_utils = "0.17.2"
+
+[dev-dependencies]
+libmarathon = { path = "../libmarathon" }
+bevy = { workspace = true }
+serde = { workspace = true }
+rkyv = { workspace = true }
+anyhow = { workspace = true }
+tracing = { workspace = true }