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>

pkg/api/http/controller/main.py

@@ -86,7 +86,9 @@ class HTTPController:
             ginst = g(self.ap, self.quart_app)
             await ginst.initialize()
 
-        frontend_path = 'web/out'
+        from ....utils import paths
+        
+        frontend_path = paths.get_frontend_path()
 
         @self.quart_app.route('/')
         async def index():

pkg/api/http/service/pipeline.py

@@ -74,11 +74,15 @@ class PipelineService:
         return self.ap.persistence_mgr.serialize_model(persistence_pipeline.LegacyPipeline, pipeline)
 
     async def create_pipeline(self, pipeline_data: dict, default: bool = False) -> str:
+        from ....utils import paths as path_utils
+        
         pipeline_data['uuid'] = str(uuid.uuid4())
         pipeline_data['for_version'] = self.ap.ver_mgr.get_current_version()
         pipeline_data['stages'] = default_stage_order.copy()
         pipeline_data['is_default'] = default
-        pipeline_data['config'] = json.load(open('templates/default-pipeline-config.json', 'r', encoding='utf-8'))
+        
+        template_path = path_utils.get_resource_path('templates/default-pipeline-config.json')
+        pipeline_data['config'] = json.load(open(template_path, 'r', encoding='utf-8'))
 
         await self.ap.persistence_mgr.execute_async(
             sqlalchemy.insert(persistence_pipeline.LegacyPipeline).values(**pipeline_data)