JGC-501 - Force non-interactive mode when CLI is invoked by an agent

[ehl-jf]

Problem

Since v2.107.0, jf api (and any other command) prompts for interactive configuration when no server profile exists and $CI is not set. This causes automation scripts driven by AI agents (Claude Code, Cursor, Gemini, etc.) to hang waiting for a yes/no answer — even when --url and auth flags are supplied on the command line.

Root cause: ShouldOfferConfig() suppresses the prompt only for $CI=true. The existing DetectExecutionContext().IsAgent infrastructure — already used for AI-help rendering — was not consulted here.

Fix

Add a second early-return guard in ShouldOfferConfig() (common/cliutils/utils.go) that mirrors the CI check:

server config exists?            → no offer (unchanged)
CI=true?                         → no offer (unchanged)
DetectExecutionContext().IsAgent? → no offer  ← new
AskYesNo(…)                      → interactive prompt (unchanged for human TTY)

When the guard fires, the CLI skips the offer and proceeds. If no URL is known (not configured, not passed via --url), the existing fast-fail error fires normally — the script gets a non-zero exit code instead of hanging.

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• All tests passed. If this feature is not already covered by the tests, I added new tests.
• All static analysis checks passed.
• This pull request is on the master branch.
• I used gofmt for formatting the code before submitting the pull request.