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.

locenice/index.php

@@ -1,10 +1,3 @@
 <?php
-// Upload this whole folder, not only this file. No Node.js or database required.
-header('Content-Type: text/html; charset=utf-8');
-header('X-Content-Type-Options: nosniff');
-$file = __DIR__ . '/app.html';
-if (!is_readable($file)) {
-    http_response_code(500);
-    exit('Chybi app.html. Nahrajte celou slozku locenice.');
-}
-readfile($file);
+
+readfile(__DIR__ . '/dum_3D_slunce.html');