Align CLI with latest backend contract and add parity hardening

[breznknecht]

Summary

• align CLI GraphQL usage with current backend contract (verdict/verdict-settings/presets/days handling)
• add grants and override commands
• add typed response decoding via execute_typed and migrate key commands away from raw response indexing
• add backend parity integration tests and contract smoke workflow
• add shared availability contract module and decode-shape guard tests

Validation

• cargo fmt --all
• cargo test -q