fix: honor active Docker context on macOS when /var/run/docker.sock is unavailable

[ish-g09]

Description

• Added ConfigureDockerHost in pkg/connectors/container_client.go to help microcks-cli connect to Docker on macOS when the default /var/run/docker.sock isn't available.
• Checks the active Docker context first via docker context inspect so it honors whatever context the user is actively running (Docker Desktop, Colima, OrbStack, etc.).
• Adds a fallback to $HOME/.docker/run/docker.sock if context inspection isn't available.
• Leaves existing behavior completely untouched if DOCKER_HOST is already set or if /var/run/docker.sock exists (like on Linux).
• Hooked this check into NewDockerClient(), PingDockerHost(), and cmd/testDryRun.go so both microcks start and microcks test --dry-run can reach Docker smoothly on modern macOS setups.
• Added comprehensive unit tests in pkg/connectors/container_client_test.go covering active context resolution, socket fallback, and platform checks.

Related issue(s)

Fixes #537

AI Disclosure

The code changes and unit tests were verified by me and I fully understand them. Used AI assistance to help structure unit test cases and mock subprocess patterns.

Testing

• go test -v -run TestConfigureDockerHost ./pkg/connectors/... : passes (6/6 tests)
• go build ./... : passes
• go test ./... : all packages pass

[Copilot]

Copilot review overview

🔵 Needs a closer look

Active-context handling has unresolved context-name and TLS/SSH compatibility issues, with missing focused macOS tests.

Review effort: Lite
Findings: None

What changed in this PR

Updates Docker endpoint discovery on macOS to support active contexts and user socket fallbacks.

Changes:

• Adds Docker context inspection and socket fallback logic.
• Applies configuration to Docker clients, ping checks, and dry-run execution.

File	Summary
pkg/​connectors/​container_client.go	Adds Docker host resolution and client integration. Requires context-name resolution, support for TLS/SSH metadata, focused macOS tests, and gofmt cleanup.
cmd/​testDryRun.go	Configures the Docker host before dry-run Testcontainers usage.

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[ish-g09]

Hey @Harsh4902,

Just opened this PR for the macOS Docker context discovery, all CI checks are green.
Saw Copilot's summary mention unit tests. Happy to add a container_client_test.go covering DOCKER_HOST precedence and resolution if you'd like. Let me know what you think whenever you get a chance to look!

[ish-g09]

Hi @Harsh4902,

Following up from the discussion on #539, I've updated the PR and added unit tests in container_client_test.go to cover the active context inspection, socket fallbacks, and platform checks for ConfigureDockerHost.

Lemme know incase i've missed on something.

[Harsh4902]

Why do we need these extra variables?

[ish-g09]

They were added as test hooks so container_client_test.go can mock exec.Command and test the macOS context inspection and socket fallback scenarios on Linux CI runners (without needing a live Docker daemon).

If you'd prefer to keep container_client.go free of package-level test variables and keep the tests simpler, happy to remove them , let me know what u think.