fix(cmd/deployment): resolve service from --deployment-id in log

[stantheman0128]

Description (required)

The issue text does not match the code. On current main (and at dc6168a, the version in the report), deployment log and deployment get skip the "Select a service" selector whenever --deployment-id is set, so that prompt never appears for this flag.

The real bug: zeabur deployment log --deployment-id <id> on its own fails with

ERROR	failed to get runtime logs: serviceID is required for runtime logs

because the command never looks up which service the deployment belongs to. Runtime logs are the default --type, so the one-flag call from the issue always fails unless --service-id is passed too.

This change fetches the deployment when --deployment-id is given without a service, and takes its project, service and environment from it. An explicit --env-id still wins. An unknown ID returns deployment <id> not found.

This is a separate code path from #278 (non-TTY prompts hanging), which is in #280.

Testing:

• New internal/cmd/deployment/log/log_test.go runs the real command with a stubbed API client. Before the fix runtime logs were requested with an empty service ID; after it they get the deployment's service and environment, in both interactive and -i=false modes.
• Linux build of main with a dummy token, stdin from /dev/null: exits 1 with the error above and no prompt.
• go test ./..., golangci-lint run ./... (0 issues), gofumpt clean. I don't have make locally, so I ran the commands it wraps. I have no real Zeabur token, so I could not fetch live logs.

Written with help from Cursor (AI). I reviewed the change and ran the tests above.

Related issues & labels (optional)

• Closes deployment log/get: --deployment-id still prompts "Select a service" despite the ID uniquely identifying the service #279
• Suggested label: bug

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