perf(ui): remove dead runtime controllers and unused stylesheet families

Two orphaned controllers in the reactive runtime targeted markup nothing
emits any more: hydrateSidebarControllers looked for .wire-sidebar-shell and
friends, which the Sidebar rewrite replaced with BEM classes earlier today,
and hydrateDropdownControllers looked for [data-wrn-dropdown], which no
component or compiler output has ever produced.

ui.css loses the matching legacy sidebar rules, the wire-mega-menu family
left behind when the MegaMenu scaffold was replaced, and a set of
self-contained application-pattern families that nothing references.

Utility layers are deliberately kept even where an individual member is not
name-checked anywhere. wire-bg-primary is documented and tested while
wire-bg-secondary is not, but they are one public family and splitting them
would be incoherent.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

docs/ui-visual-contract-0.8.json

@@ -110,6 +110,6 @@
     "packages/ui/components/progress.wrn": "ba6f4dfcc00f04f34e9533be675bb4a6200c3cdcd7d03fc597377e48520fdec7",
     "packages/ui/components/skeleton.wrn": "ceec8af147b8be08155500e378393ac7c72d819da61b62191c076c80e943d5a9",
     "packages/ui/components/spinner.wrn": "abc4ee3ede2e019289257e9009eee012c880a85839cc220fac6dbe1b780caf52",
-    "packages/ui/ui.css": "f71641efb0c98b673af70c10dbcea8e693de258ce8620b4f84c64553ea70204e"
+    "packages/ui/ui.css": "3138b86f269b6f7e67922ef2c56918444d562b11f4ae6f1fab98b63805cd78dc"
   }
 }