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_remote_creator.py

@@ -1,4 +1,4 @@
-"""Tests for application.parser.remote.remote_creator."""
+"""Tests for docsgpt.parser.remote.remote_creator."""
 
 import json
 
@@ -10,7 +10,7 @@ from unittest.mock import MagicMock
 class TestRemoteCreator:
     def test_create_loader_valid_type(self):
         """Cover line 34: returns loader instance for valid type."""
-        from application.parser.remote.remote_creator import RemoteCreator
+        from docsgpt.parser.remote.remote_creator import RemoteCreator
 
         mock_loader_cls = MagicMock()
         original_loaders = RemoteCreator.loaders.copy()
@@ -23,14 +23,14 @@ class TestRemoteCreator:
 
     def test_create_loader_invalid_type_raises(self):
         """Cover lines 32-33: raises ValueError for unknown type."""
-        from application.parser.remote.remote_creator import RemoteCreator
+        from docsgpt.parser.remote.remote_creator import RemoteCreator
 
         with pytest.raises(ValueError, match="No loader class found"):
             RemoteCreator.create_loader("nonexistent_xyz")
 
     def test_create_loader_case_insensitive(self):
         """Cover line 31: type.lower() normalization."""
-        from application.parser.remote.remote_creator import RemoteCreator
+        from docsgpt.parser.remote.remote_creator import RemoteCreator
 
         mock_loader_cls = MagicMock()
         original_loaders = RemoteCreator.loaders.copy()
@@ -48,12 +48,12 @@ class TestNormalizeRemoteData:
     back to the ``source_data`` shape each loader expects."""
 
     def test_none_passes_through(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         assert normalize_remote_data("crawler", None) is None
 
     def test_crawler_dict_with_url_key(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data(
             "crawler", {"url": "https://example.com", "provider": "crawler"}
@@ -61,20 +61,20 @@ class TestNormalizeRemoteData:
         assert result == "https://example.com"
 
     def test_url_dict_with_url_key(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data("url", {"url": "https://example.com"})
         assert result == "https://example.com"
 
     def test_url_legacy_raw_key(self):
         """Legacy rows wrapped a bare URL string as ``{"raw": ...}``."""
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data("crawler", {"raw": "https://legacy.example.com"})
         assert result == "https://legacy.example.com"
 
     def test_url_dict_with_urls_list(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data(
             "url", {"urls": ["https://a.example.com", "https://b.example.com"]}
@@ -82,7 +82,7 @@ class TestNormalizeRemoteData:
         assert result == ["https://a.example.com", "https://b.example.com"]
 
     def test_github_repo_url_key(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data(
             "github", {"repo_url": "https://github.com/arc53/DocsGPT"}
@@ -90,25 +90,25 @@ class TestNormalizeRemoteData:
         assert result == "https://github.com/arc53/DocsGPT"
 
     def test_sitemap_dict_with_url_key(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data("sitemap", {"url": "https://example.com/sitemap.xml"})
         assert result == "https://example.com/sitemap.xml"
 
     def test_plain_string_url_passes_through(self):
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         assert normalize_remote_data("crawler", "https://example.com") == "https://example.com"
 
     def test_url_dict_without_url_key_returns_none(self):
         """A URL-type loader must never receive a dict, even a malformed one."""
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         assert normalize_remote_data("crawler", {"provider": "crawler"}) is None
 
     def test_reddit_dict_serialized_to_json_string(self):
         """reddit's loader runs json.loads() — it needs a JSON string."""
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data(
             "reddit", {"client_id": "x", "search_queries": ["y"]}
@@ -118,14 +118,14 @@ class TestNormalizeRemoteData:
 
     def test_s3_dict_passes_through(self):
         """S3Loader.load_data() accepts a dict, so it is left untouched."""
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         data = {"bucket": "b", "prefix": "k"}
         assert normalize_remote_data("s3", data) == data
 
     def test_json_string_remote_data_is_parsed(self):
         """Legacy rows that stored the JSON itself as a string still resolve."""
-        from application.parser.remote.remote_creator import normalize_remote_data
+        from docsgpt.parser.remote.remote_creator import normalize_remote_data
 
         result = normalize_remote_data("crawler", '{"url": "https://example.com"}')
         assert result == "https://example.com"