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/tests/basic_macro_test.rs

@@ -0,0 +1,98 @@
+/// Basic tests for the Synced attribute macro
+use bevy::prelude::*;
+use libmarathon::networking::{
+    ClockComparison,
+    ComponentMergeDecision,
+    SyncComponent,
+};
+
+// Test 1: Basic struct with LWW strategy compiles
+// Note: No need to manually derive rkyv traits - synced attribute adds them automatically!
+#[sync_macros::synced(version = 1, strategy = "LastWriteWins")]
+#[derive(Component, Reflect, Clone, Debug, PartialEq)]
+#[reflect(Component)]
+struct Health(f32);
+
+#[test]
+fn test_health_compiles() {
+    let health = Health(100.0);
+    assert_eq!(health.0, 100.0);
+}
+
+#[test]
+fn test_health_serialization() {
+    let health = Health(100.0);
+    let bytes = health.serialize_sync().unwrap();
+    let deserialized = Health::deserialize_sync(&bytes).unwrap();
+    assert_eq!(health, deserialized);
+}
+
+#[test]
+fn test_health_lww_merge_remote_newer() {
+    let mut local = Health(50.0);
+    let remote = Health(100.0);
+
+    let decision = local.merge(remote, ClockComparison::RemoteNewer);
+    assert_eq!(decision, ComponentMergeDecision::TookRemote);
+    assert_eq!(local.0, 100.0);
+}
+
+#[test]
+fn test_health_lww_merge_local_newer() {
+    let mut local = Health(50.0);
+    let remote = Health(100.0);
+
+    let decision = local.merge(remote, ClockComparison::LocalNewer);
+    assert_eq!(decision, ComponentMergeDecision::KeptLocal);
+    assert_eq!(local.0, 50.0); // Local value kept
+}
+
+#[test]
+fn test_health_lww_merge_concurrent() {
+    let mut local = Health(50.0);
+    let remote = Health(100.0);
+
+    let decision = local.merge(remote, ClockComparison::Concurrent);
+    // With concurrent, we use hash tiebreaker
+    // Either TookRemote or KeptLocal depending on hash
+    assert!(
+        decision == ComponentMergeDecision::TookRemote ||
+            decision == ComponentMergeDecision::KeptLocal
+    );
+}
+
+// Test 2: Struct with multiple fields
+// rkyv traits are automatically added by the synced attribute!
+#[sync_macros::synced(version = 1, strategy = "LastWriteWins")]
+#[derive(Component, Reflect, Clone, Debug, PartialEq)]
+#[reflect(Component)]
+struct Position {
+    x: f32,
+    y: f32,
+}
+
+#[test]
+fn test_position_compiles() {
+    let pos = Position { x: 10.0, y: 20.0 };
+    assert_eq!(pos.x, 10.0);
+    assert_eq!(pos.y, 20.0);
+}
+
+#[test]
+fn test_position_serialization() {
+    let pos = Position { x: 10.0, y: 20.0 };
+    let bytes = pos.serialize_sync().unwrap();
+    let deserialized = Position::deserialize_sync(&bytes).unwrap();
+    assert_eq!(pos, deserialized);
+}
+
+#[test]
+fn test_position_merge() {
+    let mut local = Position { x: 10.0, y: 20.0 };
+    let remote = Position { x: 30.0, y: 40.0 };
+
+    let decision = local.merge(remote, ClockComparison::RemoteNewer);
+    assert_eq!(decision, ComponentMergeDecision::TookRemote);
+    assert_eq!(local.x, 30.0);
+    assert_eq!(local.y, 40.0);
+}