feat: model loader

[AhmedAmrNabil]

This Pr introduces the ability to load entire models yaaay
Supported model types:
AMF 3DS AC ASE ASSBIN B3D BVH COLLADA DXF CSM HMP IRRMESH IQM IRR LWO LWS MD2 MD3 MD5 MDC MDL NFF NDO OFF OBJ OGRE OPENGEX PLY MS3D COB BLEND IFC XGL FBX Q3D Q3BSP RAW SIB SMD STL TERRAGEN 3D X X3D GLTF GLB 3MF MMD

yeah alot of model types
to use this:

1. add the model to the assets directory (will discuss a convension for asset naming and location)
2. add an entry under the key "assets.models" in the config.jsonc
3. to use in entity add the component { "type": "Model Renderer", "model": "<your-model-name>" }

the model currently support reading the material of the model meaning lighting works out of the box
will need to later add a new shader called pbr shader and have the model check if it supports pbr shader then use it else use normal phong lighting (which is what we have currently in #25 branch

[Copilot]

Pull request overview

This PR adds Assimp-based full model loading to the engine and integrates it into the ECS rendering pipeline via a new Model Renderer component, including material/texture extraction for lit rendering.

Changes:

• Introduces our::Model (Assimp importer) + ModelRendererComponent, and wires model submeshes into ForwardRenderer.
• Extends lit material/texturing to support packed metallic-roughness workflows and embedded texture loading from memory.
• Updates build system to vendor/link Assimp and adds sample configs showcasing model usage.

Reviewed changes

Copilot reviewed 25 out of 28 changed files in this pull request and generated 19 comments.

Show a summary per file

File	Description
src/common/texture/texture2d.hpp	Adds a new texture unit for packed metallic/roughness.
src/common/texture/texture-utils.hpp / .cpp	Adds image upload helper + loading images from in-memory buffers (embedded textures).
src/common/systems/render-command.hpp	Extracts RenderCommand into a shared header.
src/common/systems/forward-renderer.hpp / .cpp	Integrates ModelRendererComponent submesh rendering into forward pass.
src/common/model/model.hpp / .cpp	New Assimp model importer with material/texture extraction and combined-mesh generation.
src/common/model/ai-glm-utils.hpp	Adds Assimp-to-GLM conversion helpers.
src/common/mesh/vertex.hpp	Adds bone IDs/weights fields to vertex format.
src/common/mesh/mesh.hpp	Adds bone vertex attributes + stores CPU-side copies of vertices/indices.
src/common/material/material.hpp / .cpp	Adds TextureMask + packed metal/roughness texture support to lit materials.
src/common/components/model-renderer.hpp / .cpp	New ECS component to render Model assets.
src/common/components/mesh-renderer.hpp / .cpp	Adds per-mesh relative transform storage for submeshes.
src/common/components/component-deserializer.hpp	Registers the new Model Renderer component type.
src/common/asset-loader.cpp	Adds AssetLoader<Model> deserialization and lifecycle clearing.
assets/shaders/lit.vert / lit.frag	Adds bone attributes + packed metal/roughness sampling changes in lit shader.
config/playgrounds/model.jsonc	New playground config showcasing model loading and rendering.
config/app.jsonc	Adds an example model entry (currently placed outside assets).
CMakeLists.txt / .gitmodules	Vendors and links Assimp as a new submodule dependency.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.