feat(primitives): media-editor components, category reorg, perf + type cleanup

Reorganize components into category folders (forms/canvas/overlays/etc.); add the
media-editor headless family (timeline, curve-editor, waveform, crop, color
picker, etc.); apply perf fixes (O(1) collection lookups, plain-object drag
state, gesture-leak teardown, shallowRef color state, rect caching) and replace
source `any` with proper types.

vue/primitives/src/display/date-picker/DatePickerAnchor.vue

@@ -0,0 +1,33 @@
+<script lang="ts">
+import type { PopperAnchorProps } from '../../overlays/popper';
+
+/**
+ * Optional custom anchor for positioning the popover against an element other
+ * than the trigger (e.g. a field or input group). When present, the trigger
+ * stops acting as the anchor and the content is positioned relative to this.
+ */
+export interface DatePickerAnchorProps extends PopperAnchorProps {}
+</script>
+
+<script setup lang="ts">
+import { onBeforeMount, onUnmounted } from 'vue';
+import { PopperAnchor } from '../../overlays/popper';
+import { useDatePickerRootContext } from './context';
+
+const props = defineProps<DatePickerAnchorProps>();
+
+const ctx = useDatePickerRootContext();
+
+onBeforeMount(() => {
+  ctx.hasCustomAnchor.value = true;
+});
+onUnmounted(() => {
+  ctx.hasCustomAnchor.value = false;
+});
+</script>
+
+<template>
+  <PopperAnchor v-bind="props">
+    <slot />
+  </PopperAnchor>
+</template>