feat: Add legacy shaders, model I/O, and project panel functionality

- Introduced `legacy-shaders.js` containing vertex and fragment shaders for rendering.
- Implemented `model-io.js` for parsing and encoding GLB files, ensuring compatibility with glTF 2.0.
- Created `project-panel.js` to manage project resources and survey overlays, enhancing user interaction.
- Added `solar.js` for calculating solar positions based on UTC time, latitude, and longitude.
- Developed `three-renderer.js` as a standard backend for Three.js, managing scene rendering and material synchronization.
- Included a new GLB model `dum.glb` for testing and demonstration purposes.
- Established `data_checks.mjs` for validating model data and ensuring integrity of assets.
- Created `prepare_export.py` to facilitate Blender GLB exports, maintaining material and node references.
- Added `vendor_three.py` to download and configure a local version of Three.js for the project.

locenice2/blender/prepare_model.py

@@ -0,0 +1,65 @@
+"""Run in Blender, not system Python:
+blender --background --python blender/prepare_model.py
+Creates an editable .blend next to this script. Existing scene is replaced.
+Keeps every configuration variant; helper collections are hidden in viewport.
+"""
+from pathlib import Path
+import json
+import bpy
+
+ROOT=Path(__file__).resolve().parent.parent
+SOURCE=ROOT/'models'/'dum.glb'
+TARGET=Path(__file__).resolve().parent/'dum_locenice.blend'
+if not SOURCE.is_file():
+    raise FileNotFoundError(SOURCE)
+if TARGET.exists():
+    raise FileExistsError(f'Rename or remove {TARGET} before running again.')
+bpy.ops.wm.read_factory_settings(use_empty=True)
+bpy.ops.import_scene.gltf(filepath=str(SOURCE))
+defaults=json.loads((ROOT/'data'/'catalog.json').read_text())['defaults']
+scene=bpy.context.scene
+scene.unit_settings.system='METRIC'
+scene.unit_settings.scale_length=1.0
+collections={}
+for name in ['01_Exterior','02_Interior_walls','03_Kitchen_and_furniture','04_Site','05_Cutaway_alternatives','06_Standards_alternatives']:
+    col=bpy.data.collections.new(name);scene.collection.children.link(col);collections[name]=col
+for obj in list(scene.objects):
+    if obj.type!='MESH':continue
+    props=obj
+    if props.get('stdHidden') or props.get('stdWhen') or props.get('stdBlind'):
+        key='06_Standards_alternatives'
+    elif props.get('interiorLayer') in ['cut','cutShell']:
+        key='05_Cutaway_alternatives'
+    elif props.get('interiorLayer')=='furniture':
+        key='03_Kitchen_and_furniture'
+    elif props.get('interiorLayer'):
+        key='02_Interior_walls'
+    elif props.get('siteLayer') or props.get('legacySite'):
+        key='04_Site'
+    else:key='01_Exterior'
+    for c in list(obj.users_collection):c.objects.unlink(obj)
+    collections[key].objects.link(obj)
+    # Stable ID comes from the GLB extras. Do not delete it during future editing.
+    obj['locenice_edit_note']='Keep loceniceId and configuration properties.'
+    condition=props.get('stdWhen',{})
+    hidden=bool(props.get('stdHidden')) or bool(props.get('stdBlind') and not defaults['blinds'])
+    if hasattr(condition,'items'):
+        hidden=hidden or any(defaults.get(k)!=v for k,v in condition.items())
+    obj.hide_set(hidden)
+    obj.hide_render=hidden
+collections['05_Cutaway_alternatives'].hide_viewport=True
+# Keep matching default variants visible; all alternatives remain in the file.
+note=bpy.data.texts.new('READ_ME_Locenice')
+note.write('''This is a visualisation mesh, not BIM. Units: metres.
+The source includes multiple, mutually exclusive variants in the same location.
+Use named collections to inspect them. Do not join all meshes or all materials.
+loceniceId, stdWhen, stdBlind, windowNode and interiorLayer must stay on objects.
+Detailed construction dimensions come from the project, not reference photos.
+After exporting all variants to GLB, run tools/prepare_export.py.
+Blender reorders glTF nodes, materials and textures. The included web manifest
+is indexed for the supplied GLB; the preparation tool rebinds stable IDs.
+A changed wall or cabinet also requires checking web collision volumes / camera presets.
+''')
+scene['locenice_metadata_json']=json.dumps(json.loads((ROOT/'data'/'scene.json').read_text()),ensure_ascii=False)
+bpy.ops.wm.save_as_mainfile(filepath=str(TARGET))
+print('Saved:',TARGET)