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/api/test_agent_team_sharing.py

@@ -16,7 +16,7 @@ import pytest
 
 @pytest.fixture
 def client():
-    from application.app import app as flask_app
+    from docsgpt.app import app as flask_app
 
     flask_app.config["TESTING"] = True
     return flask_app.test_client()
@@ -31,19 +31,19 @@ def _patches(sub, repo, team_access, *, prompt_name="Resolved Prompt", source_de
     if source_details is None:
         source_details = []
     return [
-        patch("application.app.handle_auth", return_value={"sub": sub}),
-        patch("application.app.resolve_roles", return_value=["user"]),
-        patch("application.api.user.agents.routes.db_readonly", lambda: _cm(Mock())),
-        patch("application.api.user.agents.routes.AgentsRepository", return_value=repo),
-        patch("application.api.user.agents.routes.team_access_for", return_value=team_access),
+        patch("docsgpt.app.handle_auth", return_value={"sub": sub}),
+        patch("docsgpt.app.resolve_roles", return_value=["user"]),
+        patch("docsgpt.api.user.agents.routes.db_readonly", lambda: _cm(Mock())),
+        patch("docsgpt.api.user.agents.routes.AgentsRepository", return_value=repo),
+        patch("docsgpt.api.user.agents.routes.team_access_for", return_value=team_access),
         # Resolve names by id (owner-agnostic) — patched so the test never
         # touches the DB; the route is what we're asserting wires them in.
         patch(
-            "application.api.user.agents.routes.resolve_prompt_name",
+            "docsgpt.api.user.agents.routes.resolve_prompt_name",
             return_value=prompt_name,
         ),
         patch(
-            "application.api.user.agents.routes.resolve_source_details",
+            "docsgpt.api.user.agents.routes.resolve_source_details",
             return_value=source_details,
         ),
     ]
@@ -160,12 +160,12 @@ class TestGetAgentResolvesNames:
 
 def _update_patches(sub, repo, team_access, can_access_mock):
     return [
-        patch("application.app.handle_auth", return_value={"sub": sub}),
-        patch("application.app.resolve_roles", return_value=["user"]),
-        patch("application.api.user.agents.routes.db_session", lambda: _cm(Mock())),
-        patch("application.api.user.agents.routes.AgentsRepository", return_value=repo),
-        patch("application.api.user.agents.routes.team_access_for", return_value=team_access),
-        patch("application.api.user.agents.routes.can_access", can_access_mock),
+        patch("docsgpt.app.handle_auth", return_value={"sub": sub}),
+        patch("docsgpt.app.resolve_roles", return_value=["user"]),
+        patch("docsgpt.api.user.agents.routes.db_session", lambda: _cm(Mock())),
+        patch("docsgpt.api.user.agents.routes.AgentsRepository", return_value=repo),
+        patch("docsgpt.api.user.agents.routes.team_access_for", return_value=team_access),
+        patch("docsgpt.api.user.agents.routes.can_access", can_access_mock),
     ]