v3.1.1 - tool description quality pass

Rewrites the 18 weakest tool descriptions (per Glama's TDQS scorecard, but genuinely for agent behaviour): every delete now states irreversibility, every ID-taking tool says which sibling tool provides the ID, and ambiguous pairs (comments vs private notes, workout PRs vs period peaks, library list vs item) are explicitly disambiguated - all while keeping descriptions terse for context economy.

Includes three honesty fixes: tp_create_equipment now documents that the API returns no ID on create (#145), tp_update_event documents its ~2-year event-resolution window, and tp_get_athlete_settings no longer claims to return FTP/zone values it doesn't.

No behaviour changes - descriptions and version only.