Add package structure and resource path utilities

- Created langbot/ package with __init__.py and __main__.py entry point
- Added paths utility to find frontend and resource files from package installation
- Updated config loading to use resource paths
- Updated frontend serving to use resource paths
- Added MANIFEST.in for package data inclusion
- Updated pyproject.toml with build system and entry points

Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>

MANIFEST.in

@@ -0,0 +1,23 @@
+include README.md
+include LICENSE
+include pyproject.toml
+
+# Include all Python packages
+recursive-include langbot *.py
+recursive-include pkg *.py
+recursive-include libs *.py
+
+# Include templates and resources
+recursive-include templates *
+recursive-include res *
+
+# Include compiled frontend files (will be added during build)
+recursive-include web/out *
+
+# Exclude unnecessary files
+global-exclude *.pyc
+global-exclude *.pyo
+global-exclude __pycache__
+global-exclude .DS_Store
+global-exclude *.so
+global-exclude *.dylib