Add initial project structure and documentation

- Created architecture documentation outlining high-level design, module organization, data flow, security model, performance considerations, testing strategy, and deployment architecture.
- Added pyproject.toml for project metadata and dependencies management.
- Introduced requirements files for development and production dependencies.
- Set up testing configuration with pytest and tox.
- Established basic directory structure for source code and tests, including __init__.py files.
- Implemented a sample web application (index.html) for drag-and-drop functionality.
- Configured VS Code workspace settings for Python development.

pytest.ini

@@ -0,0 +1,19 @@
+[pytest]
+minversion = 7.0
+testpaths = tests
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+addopts = 
+    -v
+    --cov=src/webdrop_bridge
+    --cov-report=html
+    --cov-report=term-missing
+    --strict-markers
+
+markers =
+    unit: Unit tests
+    integration: Integration tests
+    slow: Slow tests
+    windows: Windows-specific tests
+    macos: macOS-specific tests