Meaningful help text on every generated API item

Drive help text on every generated API item via strict enforcement strategy. See section 10 of #4726:

1. **For 2026R2:** Following a short transition period, any API section that does not reach a clear **beta-quality threshold**—in structure, naming, and documentation—will be withdrawn from exposure. These sections can return once they achieve that level of readiness. Any still below beta quality at dev-complete will be excluded from the release.

2. **For 2027R1:** The same process will apply, but the requirement will be **full release quality**. Only sections that meet this standard will be exposed in the public API.

Start with section 10 of #4726 and inspect how generated API items and API sections are currently exposed. Define what meaningful help text and the beta-quality threshold require, then ensure every generated item meets the requirement or that sections below the threshold are excluded from exposure.

Written by the indexing model from the issue text.