fix(cli): clarify Docker socket access errors

[ousamabenyounes]

Summary

• Detect Docker daemon permission/socket access failures separately from generic Docker unavailable errors.
• Add a short hint telling users to run Strix with Docker socket access or add their user to the docker group.
• Add regression coverage for the permission-denied Docker connection path.

Issue

Fix #482

Test verification (RED -> GREEN)

RED, test-only on upstream main:

$ uv run pytest tests/test_docker_connection_message.py -q
AssertionError: assert 'Docker socket' in ...
1 failed

GREEN, after fix:

$ uv run pytest tests/test_docker_connection_message.py -q
. [100%]
1 passed in 2.32s

Additional targeted validation:

$ uv run pytest tests/test_docker_connection_message.py tests/test_docker_client_delete.py -q
6 passed in 2.53s

$ uv run ruff check strix/interface/utils.py tests/test_docker_connection_message.py
All checks passed!

$ uv run mypy strix/interface/utils.py
Success: no issues found in 1 source file

$ uv run bandit -r strix/interface/utils.py -c pyproject.toml
No issues identified.

$ git diff --check
clean

Full-suite baseline comparison:

upstream main: uv run pytest -q -> 2 failed, 339 passed
this branch:   uv run pytest -q -> 2 failed, 340 passed

The remaining pytest failures are pre-existing in tests/test_runner_root_prompt.py with AttributeError: 'types.SimpleNamespace' object has no attribute 'runtime'.

Full Ruff baseline comparison:

upstream main: uv run ruff format --check . -> 4 files would be reformatted
this branch:   uv run ruff format --check . -> 4 files would be reformatted

upstream main: uv run ruff check . -> 2 PLC0415 lazy-import errors
this branch:   uv run ruff check . -> 2 PLC0415 lazy-import errors

[greptile-apps]

Greptile Summary

Adds clearer Docker connection diagnostics for permission-related failures.

• Detects permission-denied and operation-not-permitted Docker exceptions.
• Displays Docker socket and group-access guidance when detected.
• Adds regression coverage for the permission-denied diagnostic path.

Confidence Score: 5/5

The PR appears safe to merge.

The new diagnostic is limited to recognized permission-related Docker exceptions, preserves the existing generic error and exception behavior, and is covered by a focused regression test.

Important Files Changed

Filename	Overview
strix/interface/utils.py	Adds focused classification and guidance for Docker permission errors without changing the existing failure behavior.
tests/test_docker_connection_message.py	Verifies that a permission-denied Docker connection failure displays both socket-access and docker-group guidance.

_{Reviews (1): Last reviewed commit: "fix(cli): clarify Docker socket access e..." | Re-trigger Greptile}