[cjimti]

Changes dev/start.sh's Postgres wait and the postgres healthcheck in dev/docker-compose.yml; one bug:

1. On a fresh volume the Postgres image runs a temporary server for docker-entrypoint-initdb.d. It answers on the unix socket with the platform role and database already present. The wait connected over that socket, passed against the temporary server, and the auxiliary database check then reached it as it shut down ("the database system is shutting down"). That failed all ten acceptance jobs of the 2026-10-21 E2E Nightly (https://github.com/txn2/mcp-data-platform/actions/runs/39602596484) before any test ran, and the release candidate rules refused v1.149.0 on that nightly. The image starts the temporary server with listen_addresses='' (docker-entrypoint.sh), so the wait and the healthcheck now connect over TCP to 127.0.0.1, which only the final server answers.

Closes #2253

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.84%. Comparing base (b1def68) to head (3431326).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2254   +/-   ##
=======================================
  Coverage   94.84%   94.84%           
=======================================
  Files        1398     1398           
  Lines      113176   113176           
=======================================
+ Hits       107337   107338    +1     
+ Misses       5821     5820    -1     
  Partials       18       18           

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