feat(tarot): add interactive card flip reveal animation

Cards now start face-down and flip individually on click, with a
synthesised flip sound and staggered text fade-in. The draw button
and spread selection buttons are locked until all cards in the current
reading have been revealed. An unflipped card shows 'Click card to
reveal' as a hint.

tarot/index.html

@@ -8,6 +8,11 @@
       name="description"
       content="Draw tarot cards and receive a reading with traditional card meanings."
     />
+    <link
+      rel="preload"
+      as="image"
+      href="https://cdn.nhcarrigan.com/tarot/back.png"
+    />
     <script
       src="https://cdn.nhcarrigan.com/headers/index.js"
       async
@@ -66,6 +71,11 @@
         background: var(--witch-plum);
       }
 
+      .spread-btn:disabled {
+        opacity: 0.4;
+        cursor: not-allowed;
+      }
+
       .spread-description {
         text-align: center;
         color: var(--witch-plum);
@@ -223,13 +233,10 @@
         width: 150px;
         height: 260px;
         border-radius: 10px;
-        overflow: hidden;
         border: 2px solid var(--witch-plum);
         margin-bottom: 0.75em;
-        background: rgba(212, 165, 199, 0.08);
+        perspective: 700px;
-        display: flex;
+        position: relative;
-        align-items: center;
-        justify-content: center;
       }
 
       .card-img-wrap img {
@@ -243,6 +250,70 @@
         transform: rotate(180deg);
       }
 
+      .flip-inner {
+        width: 100%;
+        height: 100%;
+        transform-style: preserve-3d;
+        transition: transform 0.55s cubic-bezier(0.4, 0, 0.2, 1);
+        position: relative;
+      }
+
+      .flip-inner.flipped {
+        transform: rotateY(180deg);
+      }
+
+      .flip-face {
+        position: absolute;
+        inset: 0;
+        backface-visibility: hidden;
+        -webkit-backface-visibility: hidden;
+        border-radius: 8px;
+        overflow: hidden;
+      }
+
+      .flip-back img {
+        width: 100%;
+        height: 100%;
+        object-fit: cover;
+        display: block;
+      }
+
+      .flip-inner:not(.flipped) {
+        cursor: pointer;
+      }
+
+      .flip-front {
+        transform: rotateY(180deg);
+      }
+
+      .flip-front a {
+        display: block;
+        width: 100%;
+        height: 100%;
+      }
+
+      .card-details {
+        opacity: 0;
+        transition: opacity 0.4s ease;
+      }
+
+      .card-details.revealed {
+        opacity: 1;
+      }
+
+      .card-placeholder {
+        font-style: italic;
+        font-size: 0.85rem;
+        color: var(--witch-plum);
+        opacity: 0.7;
+        transition: opacity 0.3s ease;
+        text-align: center;
+      }
+
+      .card-placeholder.hidden {
+        opacity: 0;
+      }
+
       .card-name {
         font-weight: 700;
         font-size: 0.95rem;
@@ -975,6 +1046,31 @@
         }
       }
 
+      function playFlipSound() {
+        try {
+          const ctx = new (window.AudioContext || window.webkitAudioContext)();
+          const duration = 0.12;
+          const buf = ctx.createBuffer(1, Math.ceil(ctx.sampleRate * duration), ctx.sampleRate);
+          const data = buf.getChannelData(0);
+          for (let i = 0; i < data.length; i++) {
+            data[i] = (Math.random() * 2 - 1) * Math.pow(1 - i / data.length, 4);
+          }
+          const src = ctx.createBufferSource();
+          src.buffer = buf;
+          const filter = ctx.createBiquadFilter();
+          filter.type = "highpass";
+          filter.frequency.value = 900;
+          const gain = ctx.createGain();
+          gain.gain.value = 0.3;
+          src.connect(filter);
+          filter.connect(gain);
+          gain.connect(ctx.destination);
+          src.start();
+        } catch {
+          /* audio unavailable */
+        }
+      }
+
       async function renderCards(drawn, slots, positionKeys, spreadKey) {
         const area = document.getElementById("cards-area");
         area.className = "cards-area layout-" + spreadKey;
@@ -982,11 +1078,15 @@
 
         const drawBtn = document.getElementById("draw-btn");
         drawBtn.disabled = true;
+        document.querySelectorAll(".spread-btn").forEach(b => { b.disabled = true; });
 
         const meaningData = await Promise.all(
           drawn.map(card => fetchCardMeanings(card.img.replace(".png", "")))
         );
 
+        const flipInners = [];
+        const cardDetails = [];
+
         drawn.forEach((card, i) => {
           const posData = meaningData[i];
           const posKey = positionKeys[i];
@@ -1008,6 +1108,19 @@
           const imgWrap = document.createElement("div");
           imgWrap.className = "card-img-wrap";
 
+          const flipInner = document.createElement("div");
+          flipInner.className = "flip-inner";
+
+          const flipBack = document.createElement("div");
+          flipBack.className = "flip-face flip-back";
+          const backImg = document.createElement("img");
+          backImg.src = "https://cdn.nhcarrigan.com/tarot/back.png";
+          backImg.alt = "Card back";
+          flipBack.appendChild(backImg);
+
+          const flipFront = document.createElement("div");
+          flipFront.className = "flip-face flip-front";
+
           const imgLink = document.createElement("a");
           imgLink.href = `https://cdn.nhcarrigan.com/tarot/${card.img}`;
           imgLink.target = "_blank";
@@ -1020,7 +1133,14 @@
           if (card.isReversed) img.classList.add("reversed");
 
           imgLink.appendChild(img);
-          imgWrap.appendChild(imgLink);
+          flipFront.appendChild(imgLink);
+          flipInner.appendChild(flipBack);
+          flipInner.appendChild(flipFront);
+          imgWrap.appendChild(flipInner);
+          flipInners.push({ inner: flipInner, flipped: false, placeholder: null });
+
+          const details = document.createElement("div");
+          details.className = "card-details";
 
           const name = document.createElement("div");
           name.className = "card-name";
@@ -1034,15 +1154,41 @@
           meaning.className = "card-meaning";
           meaning.textContent = meaningText;
 
+          details.appendChild(name);
+          details.appendChild(orientation);
+          details.appendChild(meaning);
+          cardDetails.push(details);
+
+          const placeholder = document.createElement("div");
+          placeholder.className = "card-placeholder";
+          placeholder.textContent = "Click card to reveal";
+          flipInners[flipInners.length - 1].placeholder = placeholder;
+
           slot.appendChild(label);
           slot.appendChild(imgWrap);
-          slot.appendChild(name);
+          slot.appendChild(placeholder);
-          slot.appendChild(orientation);
+          slot.appendChild(details);
-          slot.appendChild(meaning);
           area.appendChild(slot);
         });
 
-        drawBtn.disabled = false;
+        const TEXT_DELAY = 350;
+
+        flipInners.forEach((entry, i) => {
+          entry.inner.addEventListener("click", () => {
+            if (entry.flipped) return;
+            entry.flipped = true;
+            entry.placeholder.classList.add("hidden");
+            playFlipSound();
+            entry.inner.classList.add("flipped");
+            setTimeout(() => {
+              cardDetails[i].classList.add("revealed");
+            }, TEXT_DELAY);
+            if (flipInners.every(e => e.flipped)) {
+              drawBtn.disabled = false;
+              document.querySelectorAll(".spread-btn").forEach(b => { b.disabled = false; });
+            }
+          });
+        });
       }
 
       document.querySelectorAll(".spread-btn").forEach(btn => {