feat(extract): emit WOM and WOB side-files (M2/WMO → open formats)

Extends asset_extract with two more open-format emitters:
  --emit-wom  foo.m2 (+ foo00.skin) → foo.wom
  --emit-wob  foo.wmo (+ foo_NNN.wmo groups) → foo.wob
  --emit-open now also turns these on

Originals are preserved so private servers still load .m2/.wmo
through the manifest path; the wowee runtime/editor pick up the
.wom/.wob next to them via the existing open-format search rules.

Implementation:
- New WoweeModelLoader::fromM2Bytes(m2Data, skinData) shares the
  conversion body with fromM2(path, am) via a static helper
  (convertM2ToWom). Lets the extractor convert without standing
  up an AssetManager.
- fromM2(path, am) moved to a separate translation unit
  (wowee_model_fromm2.cpp) so asset_extract doesn't have to
  link the AssetManager dependency.
- WoweeBuildingLoader::fromWMO already takes a WMOModel directly,
  so emitWobFromWmo just needs to read root + group files and
  call save().
- Group sub-files (<base>_NNN.wmo) are skipped during the walk
  since they're merged into the root WMO.

include/pipeline/wowee_model.hpp

@@ -81,6 +81,12 @@ public:
     // Convert an M2 model to WoweeModel (static geometry only, no animation)
     static WoweeModel fromM2(const std::string& m2Path, class AssetManager* am);
 
+    // Same as fromM2() but takes parsed M2 bytes + optional skin bytes
+    // directly. Lets the asset extractor convert during MPQ→loose-files
+    // without standing up an AssetManager.
+    static WoweeModel fromM2Bytes(const std::vector<uint8_t>& m2Data,
+                                   const std::vector<uint8_t>& skinData = {});
+
     // Check if a .wom exists
     static bool exists(const std::string& basePath);