feat(theme): R10 S1 — semantic status colors (danger/warn/success)

Add theme-scoped --danger/--warn/--success (+ -fg) tokens wired into the v4
@theme inline, replacing ~110 raw red/amber/emerald/green palette refs across
34 files. Fixes light-theme contrast failures (fixed Tailwind shades fell to
~1.7-3:1 on white). Status colors are scheme-independent — recognised by hue,
shifting only by theme to hold contrast (bright on dark bg, darkened on light).
Solid fills use the paired -fg text; @source inline guarantees the full -fg set
exists. IMDb rating gold kept as a deliberate decorative non-status exception.

frontend/src/components/ShareDialog.tsx

@@ -142,7 +142,7 @@ function LinkRow({ link, onChanged }: { link: ShareLink; onChanged: () => void }
           title={t("downloads.share.copy")}
           className="p-1.5 rounded-md hover:bg-surface text-muted hover:text-fg transition"
         >
-          {copied ? <Check className="w-4 h-4 text-emerald-400" /> : <Copy className="w-4 h-4" />}
+          {copied ? <Check className="w-4 h-4 text-success" /> : <Copy className="w-4 h-4" />}
         </button>
         <button
           onClick={() => {
@@ -174,7 +174,7 @@ function LinkRow({ link, onChanged }: { link: ShareLink; onChanged: () => void }
               revoke.mutate();
           }}
           title={t("downloads.share.revoke")}
-          className="p-1.5 rounded-md hover:bg-surface text-muted hover:text-red-400 transition"
+          className="p-1.5 rounded-md hover:bg-surface text-muted hover:text-danger transition"
         >
           <Trash2 className="w-4 h-4" />
         </button>
@@ -234,7 +234,7 @@ function LinkRow({ link, onChanged }: { link: ShareLink; onChanged: () => void }
                   savePass.mutate("");
               }}
               disabled={savePass.isPending}
-              className="px-2 py-1 rounded-md text-xs text-muted hover:text-red-400 transition"
+              className="px-2 py-1 rounded-md text-xs text-muted hover:text-danger transition"
             >
               {t("downloads.share.removePassword")}
             </button>