docs: drop the Cursor rule of the removed panel-ui mockups

.cursor/rules/panel-ui-system.mdc named docs/assets/panel-ui the source of
truth for mockups; that folder is gone (6099716) and the redesign's rule
(.cursor/rules/panel-design.mdc) is the one in force. The two plans that
mention the removed folders say they were removed.

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

.cursor/rules/panel-ui-system.mdc

@@ -1,22 +0,0 @@
----
-description: Panel UI mockups use the design system primitives, not a reskin of live templates.
-globs: docs/assets/panel-ui/**
-alwaysApply: false
----
-
-# Panel UI system
-
-Source of truth: [docs/assets/panel-ui/system.html](docs/assets/panel-ui/system.html) and `system.css`.
-
-Do not copy `internal/web/view/templates` into mockups. Do not mark `<main>` as `ops`/`form` to pick width. Do not fix empty columns, Host/Type height, or split Save/Delete with one-off CSS.
-
-Compose screens from `stack`, `pair`, `measure`, `fill`, `field-row`, `actions-row`:
-- Two peer jobs → `pair` (one child shrinks to `measure`).
-- Tables/logs/DNS → `fill` (nowrap + overflow-x on the card). Add-to-list is a `measure` row inside that card, not a second card above it.
-- Confirm/login/user form → `measure`.
-- Host ‖ Type and two equal inputs → `field-row` (shared grid row, not two `.code` paddings).
-- Save + Delete → `actions-row` inside the card; never submit inside `<form>` and danger after `</form>`.
-- Danger zone is the second column of the last `pair`, never a full-width `fill`.
-- Card chrome is title + optional `?` + body + actions. Help is not sprinkled later.
-- Phone: `pair` stacks; `field-row` does not; tables become lists.
-- One screen is one HTML file. Shared chrome is `shell.js`. Do not put every screen in one hash-SPA.