Implement M2 texture animation (UV scrolling) for fountain water

Parse M2TextureTransform entries and texture transform lookups from the
M2 binary, then apply per-batch UV offsets in the vertex shader using
the existing animation time base and global sequence durations.

include/pipeline/m2_loader.hpp

@@ -109,6 +109,13 @@ struct M2Batch {
     uint16_t submeshLevel = 0;      // Submesh level (0=base, 1+=LOD/alternate mesh)
 };
 
+// Texture transform (UV animation) data
+struct M2TextureTransform {
+    M2AnimationTrack translation;   // UV translation keyframes
+    M2AnimationTrack rotation;      // UV rotation keyframes (quat)
+    M2AnimationTrack scale;         // UV scale keyframes
+};
+
 // Attachment point (bone-anchored position for weapons, effects, etc.)
 struct M2Attachment {
     uint32_t id;        // 0=Head, 1=RightHand, 2=LeftHand, etc.
@@ -139,6 +146,10 @@ struct M2Model {
     std::vector<M2Texture> textures;
     std::vector<uint16_t> textureLookup;  // Batch texture index lookup
 
+    // Texture transforms (UV animation)
+    std::vector<M2TextureTransform> textureTransforms;
+    std::vector<uint16_t> textureTransformLookup;
+
     // Attachment points (for weapon/effect anchoring)
     std::vector<M2Attachment> attachments;
     std::vector<uint16_t> attachmentLookup; // attachment ID → index

include/rendering/m2_renderer.hpp

@@ -31,6 +31,7 @@ struct M2ModelGPU {
         uint32_t indexStart = 0;   // offset in indices (not bytes)
         uint32_t indexCount = 0;
         bool hasAlpha = false;
+        uint16_t textureAnimIndex = 0xFFFF; // 0xFFFF = no texture animation
     };
 
     GLuint vao = 0;
@@ -61,6 +62,11 @@ struct M2ModelGPU {
     bool hasAnimation = false;  // True if any bone has keyframes
     bool isSmoke = false;       // True for smoke models (UV scroll animation)
     bool disableAnimation = false; // Keep foliage/tree doodads visually stable
+    bool hasTextureAnimation = false; // True if any batch has UV animation
+
+    // Texture transform data for UV animation
+    std::vector<pipeline::M2TextureTransform> textureTransforms;
+    std::vector<uint16_t> textureTransformLookup;
     std::vector<int> idleVariationIndices;  // Sequence indices for idle variations (animId 0)
 
     bool isValid() const { return vao != 0 && indexCount > 0; }