fix: docsgpt up review follow-ups

- wait_healthy starts no request once the deadline is reached, and neither
  its pauses nor the requests after the first run past it; the first attempt
  still always runs (status uses a zero timeout).
- envfile writes $ as $$ inside double quotes, which Compose interpolates,
  and reads $$ back as $, so a value such as pa$w'rd reaches the container
  unchanged.
- Upgrading no longer describes the working directory as the data home.

docs/content/upgrading.mdx

@@ -121,8 +121,9 @@ alias, so nothing breaks on upgrade, but update these before the alias goes:
   and vectors under `application/` in the checkout, where they already are.
 - The backend is also a package now (`pip install docsgpt`, see
   [Install with pip](/Deploying/Pip-Install)). Runtime data lives in a data
-  home: `DOCSGPT_HOME`, else the checkout, else the directory the process
-  starts in. One consequence for a source checkout: the embedded Milvus
+  home: `DOCSGPT_HOME`, else the checkout, else `~/.docsgpt/server`
+  (`/opt/docsgpt` for root on Linux; see
+  [pip installs: data home moved](#pip-installs-data-home-moved)). One consequence for a source checkout: the embedded Milvus
   (`MILVUS_URI`) and LanceDB (`LANCEDB_PATH`) default paths now resolve under
   the checkout instead of the start directory. If you use either store at its
   default path and start DocsGPT from another directory, the old data is at