refactor: rename the application package to docsgpt

The backend import package is now docsgpt, the name it will carry on PyPI;
application was far too generic to install into anyone's site-packages.
git mv plus a mechanical rewrite of every import, dotted string and path
reference: 734 Python files, the compose files, Dockerfile, workflows, docs,
setup scripts, devcontainer, k8s manifests, vscode config, pytest and coverage
config, .gitignore. Behaviour is unchanged.

Kept for one release:
- A top-level application package whose meta-path finder resolves
  application.x.y to the already-imported docsgpt.x.y object, so old imports
  and entry points (celery -A application.app.celery,
  uvicorn application.asgi:asgi_app) keep working with a FutureWarning.
- Celery registers every application.* task name as an alias of its
  docsgpt.* task on start-up, so messages queued by the previous release still
  run. The redbeat key prefix moves to redbeat:docsgpt:v2: so schedule entries
  the previous release wrote are left unread instead of firing twice.

The backend image builds from the repository root (docker build -f
docsgpt/Dockerfile .) so it can ship the alias package; a root .dockerignore
allow-lists docsgpt/ and application/ and keeps caches, local data, .env
files, the sample index files and the Dockerfile out. Compose and the image
workflows point at the new context.

tests/parser/remote/test_share_point_loader.py

@@ -2,7 +2,7 @@
 
 from unittest.mock import patch, MagicMock
 
-from application.parser.connectors.share_point.loader import SharePointLoader
+from docsgpt.parser.connectors.share_point.loader import SharePointLoader
 
 
 def make_response(json_data=None, status_code=200, raise_error=None):
@@ -65,10 +65,10 @@ class TestSharePointLoaderProcessFile:
 class TestSharePointLoaderLoadFileById:
     """Test _load_file_by_id method."""
 
-    @patch("application.parser.connectors.share_point.loader.requests.get")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
-    @patch("application.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
+    @patch("docsgpt.parser.connectors.share_point.loader.requests.get")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
     def test_load_file_by_id_includes_size_in_select(self, mock_ensure_token, mock_auth_init, mock_get_token, mock_get):
         """Should include size field in $select parameter."""
         mock_get_token.return_value = {
@@ -96,10 +96,10 @@ class TestSharePointLoaderLoadFileById:
         params = call_args[1]["params"]
         assert "size" in params["$select"]
 
-    @patch("application.parser.connectors.share_point.loader.requests.get")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
-    @patch("application.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
+    @patch("docsgpt.parser.connectors.share_point.loader.requests.get")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
     def test_load_file_by_id_returns_document_with_size(self, mock_ensure_token, mock_auth_init, mock_get_token, mock_get):
         """Should return document with size from API response."""
         mock_get_token.return_value = {
@@ -133,10 +133,10 @@ class TestSharePointLoaderLoadFileById:
 class TestSharePointLoaderListItems:
     """Test _list_items_in_parent method."""
 
-    @patch("application.parser.connectors.share_point.loader.requests.get")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
-    @patch("application.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
+    @patch("docsgpt.parser.connectors.share_point.loader.requests.get")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
     def test_list_items_includes_size_in_select(self, mock_ensure_token, mock_auth_init, mock_get_token, mock_get):
         """Should include size field in $select parameter when listing items."""
         mock_get_token.return_value = {
@@ -168,10 +168,10 @@ class TestSharePointLoaderListItems:
         params = call_args[1]["params"]
         assert "size" in params["$select"]
 
-    @patch("application.parser.connectors.share_point.loader.requests.get")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
-    @patch("application.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
-    @patch("application.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
+    @patch("docsgpt.parser.connectors.share_point.loader.requests.get")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.get_token_info_from_session")
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointAuth.__init__", return_value=None)
+    @patch("docsgpt.parser.connectors.share_point.loader.SharePointLoader._ensure_valid_token")
     def test_list_items_folders_include_size(self, mock_ensure_token, mock_auth_init, mock_get_token, mock_get):
         """Should include size for folders as well."""
         mock_get_token.return_value = {