feat(cmd): Add '--follow' flag for start/restart

[craciunoiuc]

I wanted to do this for instance create --set autostart=true also, but I was unsure about that (was a bit controversial in a way), and it was also messing up the creation code, so I took it out.

For the tests I added a timeout field so we can force-quit out of following logs after some time.

Depends on: unikraft-cloud/go-sdk#187

Closes: TOOL-680

[Copilot]

Pull request overview

Adds --follow support to instance start and restart flows so users can stream instance logs immediately after lifecycle operations.

Changes:

• Adds Follow flags and examples for instance start and instance restart.
• Streams logs after successful start/restart operations.
• Adds timeout support to golden-test command execution and coverage for start/restart follow flows.

Reviewed changes

Copilot reviewed 4 out of 6 changed files in this pull request and generated 2 comments.

File	Description
internal/cmd/instances.go	Adds follow flags and invokes log streaming after start/restart.
cmd/unikraft/testdata/TestGolden/instances/help	Updates CLI help golden output for new flags/examples.
cmd/unikraft/main_test.go	Adds per-command timeout handling in golden tests.
cmd/unikraft/instances_test.go	Adds integration-style golden tests for start/restart follow behavior.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 6 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (2)

internal/cmd/instances.go:1467

• Using tail=0 when following after restart replays the instance's full previous log history before the new boot logs. This means restart --follow can show stale logs from before the restart and may dump a large backlog instead of following only the restarted instance's output.

	return streamInstanceLogs(ctx, stdio, started, 0, true)

cmd/unikraft/instances_test.go:227

• This test records live restart logs into the golden output. The amount and content of data collected before the 5-second timeout depends on platform/image timing and can change between runs, making the golden file nondeterministic; the test should avoid snapshotting the raw followed log stream or normalize it more aggressively.

				{
					args: []string{
						unikraftCmd, "instance", "restart",
						"--follow",
						"test-$UNIQ_INST",
					},
					timeout: 5 * time.Second,
				},

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

[craciunoiuc]

As good as it can get