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.

package-lock.json

@@ -30,7 +30,6 @@
         "react": "^19.2.4",
         "react-dom": "^19.2.4",
         "react-hook-form": "^7.71.2",
-        "react-hot-toast": "^2.6.0",
         "tailwind-merge": "^3.5.0",
         "zod": "^4.3.6"
       },
@@ -5459,6 +5458,7 @@
       "version": "3.2.3",
       "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.2.3.tgz",
       "integrity": "sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ==",
+      "devOptional": true,
       "license": "MIT"
     },
     "node_modules/damerau-levenshtein": {
@@ -6971,15 +6971,6 @@
         "url": "https://github.com/sponsors/ljharb"
       }
     },
-    "node_modules/goober": {
-      "version": "2.1.18",
-      "resolved": "https://registry.npmjs.org/goober/-/goober-2.1.18.tgz",
-      "integrity": "sha512-2vFqsaDVIT9Gz7N6kAL++pLpp41l3PfDuusHcjnGLfR6+huZkl6ziX+zgVC3ZxpqWhzH6pyDdGrCeDhMIvwaxw==",
-      "license": "MIT",
-      "peerDependencies": {
-        "csstype": "^3.0.10"
-      }
-    },
     "node_modules/gopd": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
@@ -9228,23 +9219,6 @@
         "react": "^16.8.0 || ^17 || ^18 || ^19"
       }
     },
-    "node_modules/react-hot-toast": {
-      "version": "2.6.0",
-      "resolved": "https://registry.npmjs.org/react-hot-toast/-/react-hot-toast-2.6.0.tgz",
-      "integrity": "sha512-bH+2EBMZ4sdyou/DPrfgIouFpcRLCJ+HoCA32UoAYHn6T3Ur5yfcDCeSr5mwldl6pFOsiocmrXMuoCJ1vV8bWg==",
-      "license": "MIT",
-      "dependencies": {
-        "csstype": "^3.1.3",
-        "goober": "^2.1.16"
-      },
-      "engines": {
-        "node": ">=10"
-      },
-      "peerDependencies": {
-        "react": ">=16",
-        "react-dom": ">=16"
-      }
-    },
     "node_modules/react-is": {
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",