fix(docker): chown .venv to hermes so lazy_deps can install platform packages (#24841)

The Dockerfile permissions section made /opt/hermes/.venv readable but not
writable by the hermes runtime user.  Since the 2026-05-12 policy change
moved messaging packages (discord.py, telegram, slack, etc.) out of [all]
and into lazy_deps.py, the Docker image no longer ships with them
pre-installed.  At first gateway boot, lazy_deps.ensure() tries to
`uv pip install` them into the venv but fails with EACCES because
site-packages is root-owned.

The result: every messaging platform adapter silently fails to load inside
Docker containers, producing only a cryptic "discord.py not installed"
warning despite the gateway being correctly configured.

Two-part fix:

1. Dockerfile: add /opt/hermes/.venv to the existing chown -R hermes:hermes
   line so the default (UID 10000) case works out of the box.

2. docker/entrypoint.sh: extend the needs_chown block to also re-chown the
   .venv when HERMES_UID is remapped. Without this, the build-time chown
   becomes stale when someone uses the documented HERMES_UID override in
   docker-compose.yml.

Fixes #21536
Related: #17674, #21543, #21755

docker/entrypoint.sh

@@ -39,6 +39,10 @@ if [ "$(id -u)" = "0" ]; then
         # by the mapped user on the host side.
         chown -R hermes:hermes "$HERMES_HOME" 2>/dev/null || \
             echo "Warning: chown failed (rootless container?) — continuing anyway"
+        # The .venv must also be re-chowned when UID is remapped, otherwise
+        # lazy_deps.py cannot install platform packages (discord.py, etc.).
+        chown -R hermes:hermes "$INSTALL_DIR/.venv" 2>/dev/null || \
+            echo "Warning: chown .venv failed (rootless container?) — continuing anyway"
     fi
 
     # Ensure config.yaml is readable by the hermes runtime user even if it was