A feature's menu entry carries its declared summary as its title #9681

From #9544 box 4. featureItems in src/web/layout.ts builds each absorbed feature's menu entry from its name only; the declared summary (src/actions/features.ts) is never shown outside Settings.

Done looks like:

• [x] An absorbed feature with a summary renders its menu entry with that summary as the link's title, escaped; one with no summary renders no title.
• [x] A summary longer than 200 characters is shortened at a word with an ellipsis.
• [x] A test renders the menu for a feature with and without a summary, and with a summary holding <script>, and fails on today's code.

Files: src/web/layout.ts, src/actions/features.ts, test/features*.test.ts. Risk: the menu item type may need a title field; keep it optional so other menus are unchanged. Brief: any web builder.

Parked by the crew: the check stayed red through 2 automatic tries (pull #9686 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.

Reviewed pull #9722 at its head: ticked An absorbed feature with a summary renders its menu entry with that summary as the link's title, escaped; one with no summary renders no title.; A summary longer than 200 characters is shortened at a word with an ellipsis.; A test renders the menu for a feature with and without a summary, and with a summary holding <script>, and fails on today's code..