fix(web): settings page layout pass (FE-7)

- Section header (h2 + description) and section blocks as h3; unified
  block padding and title size
- Global settings forms use label-left / control-right rows, stacked
  below md; control width fixed by type (number short, text/select
  medium, wide/textarea full)
- Per-block SaveBar pinned at the block end with dirty hint; naming
  template saves moved from the header to the bar
- Console shell uses overflow-x-clip so the sticky header and sticky
  section nav actually stick; anchor jumps re-align while async content
  loads and land below the header
- Section content uses a single minmax(0,1fr) column so wide tables
  scroll inside their card instead of widening the page
- useSettings fills missing keys from DEFAULT_SETTINGS so an older
  backend no longer crashes the metadata section

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/web/app/routes/console/layout.tsx

@@ -178,7 +178,7 @@ function ConsoleShell({ session }: { session: SessionInfo }) {
   const activeLabel = pageTitle(location.pathname) ?? PORTAL_NAME;
 
   return (
-    <div className="app-scrollbars relative isolate flex min-h-screen overflow-x-hidden bg-background">
+    <div className="app-scrollbars relative isolate flex min-h-screen overflow-x-clip bg-background">
       <div className="pointer-events-none fixed inset-0 -z-10 bg-page-glow" />
       <PrismLeak className="-z-10" />
 
@@ -245,7 +245,7 @@ function ConsoleShell({ session }: { session: SessionInfo }) {
         </header>
 
         {/* 底部留出悬浮按钮的高度,页面末尾的内容能滚到它上面 */}
-        <main className="relative flex-1 overflow-x-hidden px-4 pt-6 pb-24 md:px-6 md:pt-8">
+        <main className="relative flex-1 overflow-x-clip px-4 pt-6 pb-24 md:px-6 md:pt-8">
           <div key={location.pathname} className="mx-auto max-w-6xl motion-safe:animate-blur-in">
             <Outlet />
           </div>