feat: suppression boutique legacy + refonte achievements milestones Clickerz

- Suppression route /boutique + Boutique.jsx, BoutiqueCard.jsx, shop.json, scss associés
  (le GeneratorShop sidebar fait déjà le job)
- Refonte complète achievements : 27 milestones basés sur le GameState réel
  (paliers ressources, générateurs, prestige, évolution, easter eggs humour)
- Suppression ancien système JSON statique + AchievementsCard legacy
- Page achievements : unlocked/locked state-aware, compteur progression

Frontend/src/components/AchievementsCard.jsx

@@ -1,28 +0,0 @@
-import "../scss/components/achievementscard.scss";
-import PropTypes from "prop-types";
-
-function AchievementsCard({ name, description, image, key }) {
-  AchievementsCard.propTypes = {
-    name: PropTypes.string.isRequired,
-    description: PropTypes.string.isRequired,
-    image: PropTypes.string.isRequired,
-    key: PropTypes.number.isRequired,
-  };
-
-  return (
-    <div className="achievCardcontainer">
-      <img
-        className="achievecardpicture"
-        key={key}
-        src={image}
-        alt="cartes speciales"
-      />
-      <div className="achievetitle">
-        <p className="achievname">{name}</p>
-        <p className="achievdescription">{description}</p>
-      </div>
-    </div>
-  );
-}
-
-export default AchievementsCard;

Frontend/src/components/BoutiqueCard.jsx

@@ -1,65 +0,0 @@
-// BoutiqueCard.jsx — Legacy shop card (shop.json boosters)
-// TODO: Migrate to economy.ts generator system in a future step
-import "../scss/components/boutiquecard.scss";
-import "../scss/components/buttons.scss";
-import PropTypes from "prop-types";
-import { useGameStore } from "../store/useGameStore";
-
-export default function BoutiqueCard({
-  name,
-  price,
-  incrementValue,
-  description,
-  image,
-  type,
-}) {
-  const resources = useGameStore((s) => s.state.resources);
-
-  // Legacy shop — disabled for now, generators are in GeneratorShop
-  const canAfford = resources >= price;
-
-  return (
-    <div className="shopcardcontainer">
-      <div className="shopcontainer">
-        <div
-          className="cardpicture"
-          style={{ backgroundImage: `url(${image})` }}
-          alt={`image de ${name}`}
-        />
-        <div>
-          <div className="titlesection">
-            <p className="itemname">{name}</p>
-            <div className="price">
-              <p className="itemprice">{price}</p>
-              <div className="priceicon" />
-            </div>
-          </div>
-          <div className="description">
-            <p className="itemdesc">
-              <em>
-                {type} + {incrementValue}
-              </em>
-            </p>
-            <p className="itemdesc">{description}</p>
-          </div>
-        </div>
-        <button
-          disabled={!canAfford}
-          className="primary-button"
-          style={{ opacity: canAfford ? 1 : 0.5 }}
-        >
-          Bientôt
-        </button>
-      </div>
-    </div>
-  );
-}
-
-BoutiqueCard.propTypes = {
-  name: PropTypes.string.isRequired,
-  price: PropTypes.number.isRequired,
-  incrementValue: PropTypes.number.isRequired,
-  description: PropTypes.string.isRequired,
-  image: PropTypes.string.isRequired,
-  type: PropTypes.string.isRequired,
-};