feat: smooth view transitions, no skeleton flash

User pain point: skeleton loading.tsx files made the app feel like
a sequence of page reloads, exposing backend latency. Replaced with
a single 1px shimmer bar + crossfade via React's <ViewTransition>.

Changes:
- Enable experimental.viewTransition in next.config.ts
- Add SmoothViewTransition wrapper (ViewTransition name=page-content)
- Add LoadingFade component: thin animated bar instead of skeleton
- Add RouteAnnouncer for a11y (screen readers + focus reset)
- Add ::view-transition-old/new CSS for the crossfade (220ms, no
  jarring slide, respects prefers-reduced-motion)
- Wrap admin/tuxedo/IRD layout children in SmoothViewTransition
  (sidebar/header/footer stay mounted; only the body fades)
- Replace 19 skeleton loading.tsx files with the fade component

Result: navigation now feels like a single app, not a series of
preload-and-render events. The user never sees a 'skeleton of the
page they're about to load.'

src/app/indian-river-direct/stops/[slug]/loading.tsx

@@ -1,70 +1,6 @@
-"use client";
-
-import { motion } from "framer-motion";
+import { LoadingFade } from "@/components/transitions/LoadingFade";
 
+/** Subtle navigation indicator — see LoadingFade for rationale. */
 export default function Loading() {
-  return (
-    <div className="min-h-screen bg-stone-50/80 backdrop-blur-xl">
-      <div className="mx-auto max-w-5xl px-6 py-20">
-        {/* Back navigation skeleton */}
-        <div className="mb-10 animate-pulse">
-          <div className="h-5 w-32 rounded bg-stone-200" />
-        </div>
-
-        {/* Stop header skeleton */}
-        <div className="mb-12 animate-pulse rounded-3xl bg-white/60 border border-white/50 p-8">
-          <div className="h-3 w-32 rounded bg-blue-100 mb-4" />
-          <div className="h-16 w-80 rounded-lg bg-stone-200 mb-4" />
-          <div className="h-5 w-full max-w-md rounded bg-stone-200 mb-4" />
-          <div className="h-px w-12 bg-blue-100" />
-        </div>
-
-        {/* Stop info skeleton */}
-        <div className="mb-14 rounded-3xl bg-white/80 border border-white/50 p-8 shadow-xl">
-          <div className="grid gap-4 md:grid-cols-3">
-            {[0, 1, 2].map((i) => (
-              <motion.div
-                key={i}
-                initial={{ opacity: 0, y: 10 }}
-                animate={{ opacity: 1, y: 0 }}
-                transition={{ delay: i * 0.1 }}
-                className="flex items-start gap-4 py-4 px-5 rounded-2xl bg-stone-50"
-              >
-                <div className="h-10 w-10 rounded-xl bg-blue-50" />
-                <div className="flex-1">
-                  <div className="h-3 w-12 rounded bg-stone-200 mb-2" />
-                  <div className="h-5 w-24 rounded bg-stone-200" />
-                </div>
-              </motion.div>
-            ))}
-          </div>
-        </div>
-
-        {/* Products section skeleton */}
-        <div className="animate-pulse">
-          <div className="h-4 w-20 rounded bg-blue-100 mb-4" />
-          <div className="h-10 w-48 rounded bg-stone-200 mb-4" />
-          <div className="h-4 w-64 rounded bg-stone-200 mb-10" />
-          <div className="grid gap-8 md:grid-cols-3">
-            {[0, 1, 2].map((i) => (
-              <motion.div
-                key={i}
-                initial={{ opacity: 0, y: 20 }}
-                animate={{ opacity: 1, y: 0 }}
-                transition={{ delay: i * 0.1 }}
-                className="rounded-3xl bg-white overflow-hidden shadow-lg"
-              >
-                <div className="h-48 bg-gradient-to-br from-blue-50 to-white" />
-                <div className="p-6 space-y-3">
-                  <div className="h-6 w-3/4 rounded bg-stone-200" />
-                  <div className="h-4 w-full rounded bg-stone-100" />
-                  <div className="h-4 w-2/3 rounded bg-stone-100" />
-                </div>
-              </motion.div>
-            ))}
-          </div>
-        </div>
-      </div>
-    </div>
-  );
-}
+  return <LoadingFade />;
+}