refactor: drop toast + over-engineered extras, add inline admin feedback

Phase 1 cleanup of the personal-site revamp. Backend/architecture untouched;
changes are limited to removing unused complexity and restoring feedback.

Removals
- Toast system: delete react-hot-toast, Toaster, QueryToastBridge, lib/toast,
  the toggle/easter-egg calls, related i18n keys and the dependency.
- Contact protection: remove Turnstile + per-IP rate limiting
  (lib/contact-guard, lib/contact-protection, admin screen, form widget,
  app-config wiring, nav entry, test).
- Speculative specs: delete orders, products, downloads, project-inquiry.

Inline feedback (replaces toast, no new deps)
- Add lib/admin-feedback (withFlash/readFlash) and components/admin/admin-flash,
  rendered centrally by AdminDashboardShell.
- Emit success/error messages for media, site-settings, portfolio, smtp,
  marquee and maintenance actions; pages read them via searchParams.
- Contact form shows validation/delivery errors inline; success still
  redirects to /success.

Docs
- Fix stale paths in frontend-system-* (components/root -> components/admin,
  lib/root-navigation -> lib/admin-navigation, drop phantom src/) and remove
  contact-protection references from docs and CLAUDE.md.
- Add docs/PHASE0_DIAGNOSIS.md (diagnosis report).

Note: proxy.ts self-fetch kept intentionally; it also drives maintenance mode.

components/site/contact-form.tsx

@@ -2,12 +2,10 @@
 
 import Link from "next/link";
 
-import { ContactTurnstile } from "@/components/site/contact-turnstile";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
 import { Textarea } from "@/components/ui/textarea";
-import type { PublicContactProtectionSettings } from "@/lib/contact-protection";
 
 type ContactFormCopy = {
   name: string;
@@ -25,7 +23,6 @@ type ContactFormProps = {
   locale: string;
   previewHref: string;
   copy: ContactFormCopy;
-  protection: PublicContactProtectionSettings;
 };
 
 export function ContactForm({
@@ -33,7 +30,6 @@ export function ContactForm({
   locale,
   previewHref,
   copy,
-  protection,
 }: ContactFormProps) {
   return (
     <form action={action} className="grid gap-5">
@@ -68,10 +64,6 @@ export function ContactForm({
 
       <p className="text-sm text-muted-foreground">{copy.note}</p>
 
-      {protection.turnstile.enabled ? (
-        <ContactTurnstile siteKey={protection.turnstile.siteKey} />
-      ) : null}
-
       <div className="flex flex-wrap gap-3">
         <Button type="submit">{copy.submit}</Button>
         <Button asChild variant="outline">

components/site/contact-turnstile.tsx

@@ -1,107 +0,0 @@
-"use client";
-
-import { useEffect, useId, useRef, useState } from "react";
-
-declare global {
-  interface Window {
-    turnstile?: {
-      render: (
-        container: HTMLElement,
-        options: {
-          sitekey: string;
-          callback?: (token: string) => void;
-          "expired-callback"?: () => void;
-          "error-callback"?: () => void;
-        },
-      ) => string;
-    };
-  }
-}
-
-type ContactTurnstileProps = {
-  siteKey: string;
-};
-
-export function ContactTurnstile({ siteKey }: ContactTurnstileProps) {
-  const containerRef = useRef<HTMLDivElement | null>(null);
-  const [token, setToken] = useState("");
-  const [error, setError] = useState("");
-  const widgetId = useId();
-
-  useEffect(() => {
-    if (!siteKey || !containerRef.current) {
-      return undefined;
-    }
-
-    let cancelled = false;
-
-    function renderWidget() {
-      if (cancelled || !containerRef.current || !window.turnstile) {
-        return;
-      }
-
-      if (containerRef.current.dataset.widgetMounted === widgetId) {
-        return;
-      }
-
-      containerRef.current.innerHTML = "";
-      window.turnstile.render(containerRef.current, {
-        sitekey: siteKey,
-        callback: (nextToken) => {
-          setToken(nextToken);
-          setError("");
-        },
-        "expired-callback": () => {
-          setToken("");
-          setError("Verification expired. Please try again.");
-        },
-        "error-callback": () => {
-          setToken("");
-          setError("Verification could not be completed.");
-        },
-      });
-      containerRef.current.dataset.widgetMounted = widgetId;
-    }
-
-    function ensureScript() {
-      const existingScript = document.querySelector<HTMLScriptElement>(
-        'script[src="https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit"]',
-      );
-
-      if (existingScript) {
-        if (window.turnstile) {
-          renderWidget();
-        } else {
-          existingScript.addEventListener("load", renderWidget, { once: true });
-        }
-
-        return;
-      }
-
-      const script = document.createElement("script");
-      script.src = "https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit";
-      script.async = true;
-      script.defer = true;
-      script.addEventListener("load", renderWidget, { once: true });
-      document.head.appendChild(script);
-    }
-
-    ensureScript();
-
-    return () => {
-      cancelled = true;
-    };
-  }, [siteKey, widgetId]);
-
-  if (!siteKey) {
-    return null;
-  }
-
-  return (
-    <div className="space-y-2">
-      <div ref={containerRef} />
-      <input type="hidden" name="turnstileToken" value={token} />
-      {error ? <p className="text-xs text-destructive">{error}</p> : null}
-    </div>
-  );
-}