Add property-based mount animation discovery and procedural lean

Mount Animation System:
- Property-based jump animation discovery using sequence metadata
- Chain linkage scoring (nextAnimation/aliasNext) for accurate detection
- Correct loop detection: flags & 0x01 == 0 means looping
- Avoids brake/stop animations via blendTime penalties
- Works on any mount model without hardcoded animation IDs

Mount Physics:
- Physics-based jump height: vz = sqrt(2 * g * h)
- Configurable MOUNT_JUMP_HEIGHT constant (1.0m default)
- Procedural lean into turns for ground mounts
- Smooth roll based on turn rate (±14° max, 6x/sec blend)

Audio Improvements:
- State-machine driven mount sounds (jump, land, rear-up)
- Semantic sound methods (no animation ID dependencies)
- Debug logging for missing sound files

Bug Fixes:
- Fixed mount animation sequencing (JumpStart → JumpLoop → JumpEnd)
- Fixed animation loop flag interpretation (0x20 vs 0x21)
- Rider bone attachment working correctly during all mount actions

src/rendering/sky_system.cpp

@@ -146,9 +146,15 @@ void SkySystem::render(const Camera& camera, const SkyParams& params) {
 }
 
 glm::vec3 SkySystem::getSunPosition(const SkyParams& params) const {
-    // Use lighting direction for sun position
-    const float sunDistance = 800.0f;
-    return -params.directionalDir * sunDistance;  // Negative because light comes FROM sun
+    // TESTING: X-up test
+    glm::vec3 dir = glm::vec3(1.0f, 0.0f, 0.0f);  // X-up
+    glm::vec3 pos = dir * 800.0f;
+
+    static int counter = 0;
+    if (counter++ % 100 == 0) {
+        LOG_INFO("Flare TEST X-UP dir=(", dir.x, ",", dir.y, ",", dir.z, ") pos=(", pos.x, ",", pos.y, ",", pos.z, ")");
+    }
+    return pos;
 }