fix(docker): avoid host PATH interpolation

[dpersek]

Summary

Docker Compose no longer injects the host process PATH into the MCP server containers. This prevents Windows host paths from replacing the Linux image PATH that startup commands rely on.

The Dockerfiles already bake /root/.local/bin into the image PATH, so the compose-level override was redundant and could break startup when ${PATH} expanded to something like C:\Windows\system32;C:\Windows.

Type of Change

• Bug fix
• New feature
• Performance improvement
• Documentation/Tests

Objective

Fix the Docker Compose startup failure reported in #1623 without changing Dockerfile install behavior, service commands, or runtime configuration.

Testing

• Unit tests added/updated
• Integration tests added/updated
• All existing tests pass

Validation run:

• PATH='C:\Windows\system32;C:\Windows' docker compose -f mcp_server/docker/docker-compose.yml config --quiet
• PATH='C:\Windows\system32;C:\Windows' docker compose -f mcp_server/docker/docker-compose-falkordb.yml config --quiet
• PATH='C:\Windows\system32;C:\Windows' docker compose -f mcp_server/docker/docker-compose-neo4j.yml config --quiet
• git diff --check upstream/main

I also checked rendered config output for all three compose files with the same simulated Windows-style host PATH. After this change, the compose files no longer render a container PATH override.

Not run: full test suite / make lint. This change only removes compose-file PATH interpolation; no Python code changed. GitHub's ruff check is passing on the draft PR.

Breaking Changes

• This PR contains breaking changes

Scope

• Limited to the three MCP Docker Compose files named in docker-compose files interpolate host $PATH into container env, crashing startup on Windows #1623.
• No Dockerfile, Python, dependency, or documentation changes.
• Does not address the older rootless /root/.local/bin permission issue from MCP server fails to start via Docker Compose #665 or the separate Dockerfile-focused PR fix(docker): install uv system-wide so runtime works under non-root #981.

Caveats

• Validation covered Docker Compose rendering/configuration, not end-to-end container startup.
• No unit tests were added because this is compose-file interpolation behavior rather than Python runtime behavior.

Checklist

• Code follows project style guidelines (make lint passes)
• Self-review completed
• Documentation updated where necessary
• No secrets or sensitive information committed

Related Issues

Fixes #1623

[zep-cla-assistant]

All contributors have signed the CLA ✍️ ✅
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[dpersek]

I have read the CLA Document and I hereby sign the CLA behalf on myself, e-mail: syntaxsawdust.cgoco@passmail.net

[Naseem77]

@dpersek Confirmed the leak: my host paths showed up inside the container via docker compose config. Your change fixes it and the image Dockerfile already sets PATH. LGTM!