[FEATURE] A setting to hide or collapse "hook success" lines (suppressOutput is documented as having no effect)

Problem

With several plugins installed, every prompt, session start and tool call prints one "<Event> hook success" line per hook that ran. On one machine (15 plugins enabled) a single user prompt runs 4 UserPromptSubmit hooks, a session start runs 6 SessionStart hooks, and every tool call runs 3 or more PostToolUse hooks. The user cannot act on any of these lines: they only say a hook finished without error.

What exists today

• A successful hook's own stdout is already kept out of the transcript for most events.
• The hooks reference documents suppressOutput in the JSON output table as having no effect ("Claude Code accepts the field but doesn't act on it").
• The only ways to reduce the lines are to remove hooks, narrow them with matcher / if, or set disableAllHooks, which turns off everything that depends on hooks.
• Failures show as hook error, which is the right behavior and should stay.

Request

A user setting (for example hooks.showSuccessLines: false, or a hookSuccessLines: "hidden" | "collapsed" | "shown" value) that hides or collapses the completion lines for successful hooks while still surfacing errors and still logging the run to the debug log. A per-hook opt-out would also work, but plugin authors are not the people who see the noise, so a user-level switch matters most.

Related, closed without a setting: #9610, #9602 (duplicated or stacking hook messages).