render map objects: decode compiled W3DMesh art, skin and draw over terrain

Read the buildings and props a map places from its compiled art (the
uncompressed worldbuilder stream + embedded DDS textures):

- ra3.models: BAB asset-stream parser (lazy slices), W3DMesh + D3DHierarchy
  decode, DDS (DXT1/3/5 + uncompressed) decode, per-mesh bone remap and
  bind-pose single-joint skinning, flattened to one world-space triangle soup.
- ra3.map: parse the ObjectsList chunk into (type, x, y, z, angle).
- ra3.terrain: render3d rasterises the scene over the raymarched terrain with
  a z-buffer; gpu_terrain carries the scene for the GPU backends.
- ra3.vulkan: second pipeline + depth attachment, terrain.frag writes
  gl_FragDepth, and a small depth bias keeps ground decals from z-fighting.
- objects.fx shaders (compiled to SPIR-V), embedded like scene/terrain.

Only opaque parts are drawn: FX-light billboards (DefaultW3D.fx / BasicW3D.fx)
and damage-fill shells (BuildingsGenericDamageFill.fx) are skipped, since the
latter paint the wrecked interior (e.g. orange CBBuilding_Wood) over the shell.

Ground-decal meshes with no diffuse role and the Road templates themselves are
still not drawn.

docs/ARCHITECTURE.md

@@ -79,7 +79,7 @@ umbrella module re-exports the SDK; applications import `ra3` only.
 ```
 
 The current concrete modules (`ra3.core`, `ra3.logic`, `ra3.data`,
-`ra3.skirmish`, `ra3.fs`, `ra3.map`, `ra3.terrain`, `ra3.render`, `ra3.ui.*`,
+`ra3.skirmish`, `ra3.fs`, `ra3.map`, `ra3.terrain`, `ra3.models`, `ra3.render`, `ra3.ui.*`,
 `ra3.vulkan.*`, `ra3.dx.*`, `ra3.webgpu.*`, `ra3.wasmgl.*`, `ra3.display`, `ra3.game`, `ra3.client`, and the
 vendored `ender.log`) are the **seeds** of the
 target modules below. `ra3.skirmish` and `ra3.game` will be absorbed into
@@ -206,10 +206,11 @@ Mirrors SAGE `GameEngine/Common`. Everything else speaks this.
   - `[ ]` DDS / DXT compressed textures `(v0.5)`
   - `[ ]` atlas + mip generation, gutter padding (GPU) `[~]`
   - `[ ]` async upload / streaming `(v0.6)`
-- **F2 Models** `[ ]` `!!`
-  - `[ ]` W3D container parse (chunks, hierarchy, meshes) `(v0.6)`
-  - `[ ]` materials, shaders, texture references
-  - `[ ]` LOD sets, collision meshes
+- **F2 Models** `[~]`
+  - `[x]` compiled `W3DMesh` decode (vertex buffer + D3D9 declaration + triangle list) from the BAB static/worldbuilder stream
+  - `[x]` embedded DDS textures (DXT1/3/5 + uncompressed RGB) → ARGB
+  - `[x]` `W3DHierarchy` decode + static bind-pose skinning (bone-space vertices)
+  - `[ ]` W3D container/hierarchy animation, LOD sets, collision meshes `!!` `(v0.6)`
 - **F3 Animation** `[ ]` `!!`
   - `[ ]` W3D animation chunks, bone poses `(v0.6)`
   - `[ ]` blend trees / transition animations
@@ -533,8 +534,10 @@ Mirrors SAGE `GameEngine/Common`. Everything else speaks this.
 - **F3 Terrain render** `[~]`
   - `[x]` top-down software + GPU heightfield with blend ramp + gutter atlas
   - `[ ]` perspective terrain mesh, LOD, cliff, water `(v0.6)`
-- **F4 Model render** `[ ]` `!!`
-  - `[ ]` W3D draw, skinning, materials, team colors `(v0.6)`
+- **F4 Model render** `[~]`
+  - `[x]` static map-object triangle soup, world-space, depth-tested over the terrain (Vulkan + software)
+  - `[x]` bind-pose skinning (bone-space vertices) + ground-decal depth bias
+  - `[ ]` animated W3D draw, materials, team colors `!!` `(v0.6)`
   - `[ ]` shadows, decals, ground marks `(v0.6)`
 - **F5 VFX** `[ ]`
   - `[ ]` particle systems, beams, muzzle flashes, explosions `(v0.6)`
@@ -575,8 +578,9 @@ Mirrors SAGE `GameEngine/Common`. Everything else speaks this.
   - `[ ]` formal RHI integration (see M16 F1) `(v0.6)`
 - **F2 Terrain presentation** `[D]`
   - `[x]` GPU heightfield raymarch, mipmapped atlas, gutter, retail blend ramp
-- **F3 Materials & pipelines** `[ ]`
-  - `[ ]` model/particle/HUD pipelines `(v0.6)`
+- **F3 Materials & pipelines** `[~]`
+  - `[x]` static-model pipeline (vertex/index buffers, texture array, depth test)
+  - `[ ]` particle/HUD pipelines `(v0.6)`
 - **F4 Null fallback** `[D]`
   - `[x]` report failure when no Vulkan loader is present