feat: add equipment, achievements, and visual polish

- Equipment system: 12 items across weapon/armour/trinket slots with
  common/rare/epic/legendary rarities; starter commons auto-equipped,
  higher tiers drop from boss victories
- Achievement system: 15 milestones with typed conditions; checked
  each tick and crystal rewards applied automatically
- Achievement toast: slide-in notification, auto-dismisses after 4s
- Floating click text: +X gold floats on each manual click
- Expanded quests (9 total) and upgrades (12 total)
- Upgrade panel now shows locked upgrades so players can see their
  progression path
- formatNumber utility (K/M/B/T) used consistently across all panels
- Backfill logic for existing saves to add new content gracefully
- types package now emits .d.ts declarations

apps/web/src/components/game/ClickArea.tsx

@@ -1,8 +1,38 @@
+import { useCallback, useRef, useState } from "react";
 import { useGame } from "../../context/GameContext.js";
 import { calculateClickPower } from "../../engine/tick.js";
+import { formatNumber } from "../../utils/format.js";
+
+interface FloatText {
+  id: number;
+  x: number;
+  y: number;
+  text: string;
+}
 
 export const ClickArea = (): React.JSX.Element => {
   const { state, handleClick } = useGame();
+  const [floats, setFloats] = useState<FloatText[]>([]);
+  const nextIdRef = useRef(0);
+
+  const handleClickWithFloat = useCallback(
+    (e: React.MouseEvent<HTMLButtonElement>) => {
+      if (!state) return;
+      const rect = e.currentTarget.getBoundingClientRect();
+      const x = e.clientX - rect.left;
+      const y = e.clientY - rect.top;
+      const id = nextIdRef.current++;
+      const clickPower = calculateClickPower(state);
+
+      setFloats((prev) => [...prev, { id, x, y, text: `+${formatNumber(clickPower)}` }]);
+      handleClick();
+
+      setTimeout(() => {
+        setFloats((prev) => prev.filter((f) => f.id !== id));
+      }, 900);
+    },
+    [state, handleClick],
+  );
 
   if (!state) return <div className="click-area-placeholder" />;
 
@@ -11,15 +41,26 @@ export const ClickArea = (): React.JSX.Element => {
   return (
     <section className="click-area">
       <h2>Guild Hall</h2>
-      <button
-        className="click-button"
-        onClick={handleClick}
-        type="button"
-        aria-label={`Click to earn ${clickPower.toFixed(1)} gold`}
-      >
-        ⚔️
-      </button>
-      <p className="click-power">+{clickPower.toFixed(1)} gold per click</p>
+      <div className="click-button-wrapper">
+        <button
+          className="click-button"
+          onClick={handleClickWithFloat}
+          type="button"
+          aria-label={`Click to earn ${formatNumber(clickPower)} gold`}
+        >
+          ⚔️
+        </button>
+        {floats.map((float) => (
+          <span
+            key={float.id}
+            className="click-float"
+            style={{ left: float.x, top: float.y }}
+          >
+            {float.text}
+          </span>
+        ))}
+      </div>
+      <p className="click-power">+{formatNumber(clickPower)} gold/click</p>
     </section>
   );
 };