fix(rename): second review pass on the package rename

- The post-task reclaim skip recognises the legacy application.* embed name,
  so query embeds queued by the previous release do not pay a full collect.
- The Azure compose file mounts host data on /app/{indexes,inputs,vectors},
  where the process actually reads and writes; it mounted /app/application/...
  before the rename and /app/docsgpt/... after it, and nothing wrote to either.
- The offline image check triggers on docsgpt/requirements*.txt again;
  dependabot's pip entry points at docsgpt/.
- install_hint() and its docstring name docsgpt/requirements-<extra>.txt;
  the test asserts the full path.
- application/vectors/ stays ignored: the compose files still mount it.
- The durability QA script quiets the docsgpt logger tree.
- Upgrade note: the three renamed source-sync entries start their timers
  from the upgrade.

docsgpt/core/optional_deps.py

@@ -1,7 +1,7 @@
 """Optional dependency extras and the one place their install hints come from.
 
 Heavy or niche packages are not installed by default. Each extra maps to a
-pyproject extra and to an exported ``application/requirements-<extra>.txt``,
+pyproject extra and to an exported ``docsgpt/requirements-<extra>.txt``,
 so a missing module can always be explained with the exact command to run.
 """
 
@@ -28,7 +28,7 @@ _MODULE_TO_EXTRA: Dict[str, str] = {
 def install_hint(extra: str) -> str:
     """Install command for ``extra``, for error messages and logs."""
     return (
-        f"pip install -r application/requirements-{extra}.txt "
+        f"pip install -r docsgpt/requirements-{extra}.txt "
         f"(or: uv sync --extra {extra}; Docker: --build-arg EXTRAS={extra})"
     )