feat: add floating quick-action buttons

apps/web/app/components/FloatingButtons.vue

@@ -0,0 +1,94 @@
+<script lang="ts" setup>
+const colorMode = useColorMode()
+const showScrollTop = shallowRef(false)
+
+function toggleTheme() {
+  colorMode.preference = colorMode.value === "dark" ? "light" : "dark"
+}
+
+function scrollToTop() {
+  window.scrollTo({ top: 0, behavior: "smooth" })
+}
+
+function onScroll() {
+  showScrollTop.value = window.scrollY > 400
+}
+
+onMounted(() => window.addEventListener("scroll", onScroll, { passive: true }))
+onUnmounted(() => window.removeEventListener("scroll", onScroll))
+</script>
+
+<template>
+  <button
+    type="button"
+    class="float-btn float-theme"
+    :class="{ raised: showScrollTop }"
+    :title="colorMode.value === 'dark' ? 'Switch to light mode' : 'Switch to dark mode'"
+    @click="toggleTheme"
+  >
+    <span v-if="colorMode.value === 'dark'">☀</span>
+    <span v-else>◐</span>
+  </button>
+
+  <Transition name="slide-up">
+    <button
+      type="button"
+      v-if="showScrollTop"
+      class="float-btn float-scroll"
+      title="Scroll to top"
+      @click="scrollToTop"
+    >
+      ↑
+    </button>
+  </Transition>
+</template>
+
+<style scoped>
+.float-btn {
+  position: fixed;
+  right: 24px;
+  z-index: 200;
+  width: 36px;
+  height: 36px;
+  background: var(--bg-subtle);
+  border: 1px solid var(--border);
+  color: var(--text-muted);
+  font-family: inherit;
+  font-size: 15px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+}
+.float-btn:hover {
+  border-color: var(--accent);
+  color: var(--accent);
+}
+
+.float-theme {
+  bottom: 24px;
+  transition:
+    bottom 0.2s ease,
+    border-color 0.12s,
+    color 0.12s;
+}
+.float-theme.raised {
+  bottom: 68px; /* 24px base + 36px btn + 8px gap */
+}
+
+.float-scroll {
+  bottom: 24px;
+}
+
+.slide-up-enter-active,
+.slide-up-leave-active {
+  transition:
+    opacity 0.2s ease,
+    transform 0.2s ease;
+}
+.slide-up-enter-from,
+.slide-up-leave-to {
+  opacity: 0;
+  transform: translateY(10px);
+}
+</style>