Wire `with:` inputs from caller workflows to called workflows via
`inputs.*` context, resolve `on.workflow_call.inputs` defaults, and
propagate `on.workflow_call.outputs` back so downstream jobs can
access `needs.<callerJobId>.outputs.*`. Also fixes intra-workflow
`needs.*` resolution for composite job IDs.
Adds smoke test, unit tests, /validate command, and CLAUDE.md agent rules.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>