Revert to guest-cart architecture, drop in-site auth/checkout

Per api.meshkee.com/docs/website/AI_PROMPT.md's hard rules (which an
earlier pass on this branch missed): login, register, OTP, the real
cart, addresses, and payment are the customer dashboard's job
(customer.sanihome.ir), not this storefront's. This site should only
ever run a local guest mini-cart and hand off to the dashboard.

- Remove: AuthContext, LoginModal, lib/auth.ts, lib/cart.ts (the real
  /businesses/{id}/cart integration), and the /checkout page entirely.
- Add lib/guestCart.ts: localStorage + shared cookie
  (meshkee-guest-cart, Domain=.sanihome.ir) cart, storeItemVariantId
  keyed, matching the spec's line shape and ~3500-char cookie-size
  cutoff.
- CartContext is now a thin React wrapper over the guest cart (no
  server round-trip, so add/update/remove are synchronous); CartPopup's
  "Continue" builds the exact customer.sanihome.ir/checkout/cart
  (or /login?redirect=...) URL from the spec, base64url-encoding the
  cart and detecting an existing dashboard session via the shared
  meshkee_customer_access_token cookie.
- ProductCard and ProductPurchasePanel add to the guest cart directly;
  no login gate on add-to-cart anymore.
- Comments panel is a plain guest name/email/text form again (the
  comments API never required auth — gating it on the now-removed
  login system was wrong regardless).
- CONTEXT.md rewritten to document the guest-cart contract explicitly
  and flag this exact mistake so it doesn't get reintroduced.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/components/product/ProductTabs.tsx

@@ -2,7 +2,6 @@
 
 import { useState } from "react";
 import { EmptyState } from "@/components/ui/EmptyState";
-import { useAuth } from "@/context/AuthContext";
 import { postComment, type EntityComment, type TechnicalInfoField } from "@/lib/meshkee";
 
 type Tab = "specs" | "review" | "comments";
@@ -19,23 +18,23 @@ function formatDate(iso?: string) {
 }
 
 function CommentsPanel({ entityId, initialComments }: { entityId: string; initialComments: EntityComment[] }) {
-  const { user, openLoginModal } = useAuth();
   const [comments, setComments] = useState(initialComments);
+  const [name, setName] = useState("");
+  const [email, setEmail] = useState("");
   const [text, setText] = useState("");
   const [busy, setBusy] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
   const handleSubmit = async (event: React.FormEvent) => {
     event.preventDefault();
-    if (!user || !text.trim()) return;
+    if (!name.trim() || !text.trim()) return;
     setBusy(true);
     setError(null);
-    const authorName = [user.firstName, user.lastName].filter(Boolean).join(" ") || "کاربر";
     const res = await postComment({
       entityType: "product",
       entityId,
-      authorName,
-      authorEmail: user.email,
+      authorName: name.trim(),
+      authorEmail: email.trim() || undefined,
       text: text.trim(),
     });
     setBusy(false);
@@ -43,43 +42,46 @@ function CommentsPanel({ entityId, initialComments }: { entityId: string; initia
       setError(res.message ?? "ثبت نظر ناموفق بود.");
       return;
     }
-    setComments((prev) => [{ id: `local-${Date.now()}`, authorName, text: text.trim() }, ...prev]);
+    setComments((prev) => [{ id: `local-${Date.now()}`, authorName: name.trim(), text: text.trim() }, ...prev]);
     setText("");
   };
 
   return (
     <div>
-      {user ? (
-        <form onSubmit={handleSubmit} className="mb-6 space-y-3">
-          <textarea
+      <form onSubmit={handleSubmit} className="mb-6 space-y-3">
+        <div className="grid gap-3 sm:grid-cols-2">
+          <input
             required
-            rows={3}
-            value={text}
-            onChange={(e) => setText(e.target.value)}
-            placeholder="نظر خود را درباره این محصول بنویسید..."
-            className="w-full rounded-xl border border-border bg-background p-3 text-sm outline-none transition-colors focus:border-red"
+            placeholder="نام شما"
+            value={name}
+            onChange={(e) => setName(e.target.value)}
+            className="w-full rounded-lg border border-border bg-background px-3 py-2 text-sm outline-none transition-colors focus:border-red"
+          />
+          <input
+            type="email"
+            placeholder="ایمیل (اختیاری)"
+            value={email}
+            onChange={(e) => setEmail(e.target.value)}
+            className="w-full rounded-lg border border-border bg-background px-3 py-2 text-sm outline-none transition-colors focus:border-red"
           />
-          {error && <p className="text-xs text-red-dark">{error}</p>}
-          <button
-            type="submit"
-            disabled={busy || !text.trim()}
-            className="rounded-lg bg-red px-5 py-2 text-sm font-medium text-white transition-colors hover:bg-red-dark disabled:cursor-not-allowed disabled:opacity-60"
-          >
-            {busy ? "در حال ثبت..." : "ثبت نظر"}
-          </button>
-        </form>
-      ) : (
-        <div className="mb-6 flex flex-wrap items-center justify-between gap-3 rounded-xl bg-background p-4 text-sm">
-          <span className="text-muted">برای ثبت نظر ابتدا وارد حساب کاربری خود شوید.</span>
-          <button
-            type="button"
-            onClick={openLoginModal}
-            className="rounded-lg bg-red px-4 py-1.5 text-xs font-medium text-white transition-colors hover:bg-red-dark"
-          >
-            ورود
-          </button>
         </div>
-      )}
+        <textarea
+          required
+          rows={3}
+          value={text}
+          onChange={(e) => setText(e.target.value)}
+          placeholder="نظر خود را درباره این محصول بنویسید..."
+          className="w-full rounded-xl border border-border bg-background p-3 text-sm outline-none transition-colors focus:border-red"
+        />
+        {error && <p className="text-xs text-red-dark">{error}</p>}
+        <button
+          type="submit"
+          disabled={busy || !name.trim() || !text.trim()}
+          className="rounded-lg bg-red px-5 py-2 text-sm font-medium text-white transition-colors hover:bg-red-dark disabled:cursor-not-allowed disabled:opacity-60"
+        >
+          {busy ? "در حال ثبت..." : "ثبت نظر"}
+        </button>
+      </form>
 
       {comments.length === 0 ? (
         <EmptyState message="هنوز نظری برای این محصول ثبت نشده است." />