Add suggest command

[icntswm]

Adds skillcheck suggest <report.json>, which reads the confusion data of a run --json report and asks the model to rewrite the descriptions of the confused skills.

• Evidence per skill: failed runs where it was expected or loaded in a neighbour's place (up to 8 queries), plus passing queries that must keep working (up to 5).
• Errored and diagnosed runs are ignored. Skills the agent did not see are skipped with a note to fix the setup instead.
• Suggestions over 1024 characters, unchanged, duplicate or for unknown skills are dropped.
• Output: the diff of old and new descriptions with the reason; --json writes {file, suggestions, costUsd}. --skill limits the targets.
• Docs: docs/commands.md, README.