Support --output-rule with --server-side

[jbpros]

kosli evaluate trail|trails --output-rule works locally, but not with --server-side, so the CLI refuses the combination for now.

Why

The server-side path only returns allow and violations:

• opa-lambda filters them: evaluator/evaluator.go only queries those two rules.
• server passes result through as-is.
• CLI only reads allow and violations back (internal/evaluations/client.go).

What it takes

1. opa-lambda: query the extra rules too.
2. server: accept the rule list in POST /evaluations and pass it to the lambda.
3. CLI: send --output-rule, read the extra keys, drop the refusal.

Bonus

kosli evaluate policy already stores the whole result in the decision attestation. So once the lambda returns extra rules, a policy's report gets recorded as evidence for free.

To keep in mind

• Match the local behaviour: a missing rule fails, an undefined one gives null.
• The lambda has a 6 MB payload limit, and big reports add up.