docker ps --format json / --no-trunc should passthrough

[PLNech]

Context

Found by agentic fuzzer (FUZZ-006 residual). The smart passthrough fix (d10621e) handles -q, --quiet, and --format flags, but two cases still fail:

• docker ps --no-trunc - RTK applies its compact format template, truncating the full IDs the user explicitly requested
• docker ps --format json - RTK's format template overrides the user's JSON request

Fix

Add --no-trunc to the content-flag passthrough list in container.rs. The --format json case should already be caught by the format flag check - needs investigation.

Severity

Low - workaround: rtk proxy docker ps --no-trunc