design: the preflight mockup goes - the page was dropped on 2026-10-13

Owner, 2026-10-18: "Чисти этот хвост." Preflight as a page of its own was
dropped on 2026-10-13 (roadmap.md § Dropped): its installation checks went
to Server › Health (health-setup-checks, 2.11.0) and its test e-mail to a
form of its own (test-email, 2.12.0). The mockup still drew it and every
mockup's navigation still linked it.

- panel/src/preflight.html and its built page deleted; build.py's Server
  group loses the entry, and the 39 pages are rebuilt (each one only loses
  that link, in the navbar and the touch menu).
- check.py --write: outlines.json loses the "preflight" key; 31 screens,
  0 violations.
- index.html and panel-redesign.md § Room for roadmap items no longer list it.

The guard's deferredScreens entry goes in the next commit, on its own.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/assets/panel-redesign/panel/outlines.json

@@ -380,11 +380,6 @@
    ]
   }
  ],
- "preflight": [
-  "head+postmark+actions",
-  "box[Checks]:table",
-  "box[Send a test e-mail]:body"
- ],
  "settings": [
   "head+actions",
   {