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/selection/select/SelectGroup.vue

@@ -0,0 +1,36 @@
+<script lang="ts">
+import type { PrimitiveProps } from '../../internal/primitive';
+
+/**
+ * Groups a set of related items under a shared label. Renders as a
+ * `role="group"` and provides an id so a child `SelectLabel` can label the
+ * group for assistive technology.
+ */
+export interface SelectGroupProps extends PrimitiveProps {}
+</script>
+
+<script setup lang="ts">
+import { useForwardExpose } from '@robonen/vue';
+
+import { useId } from '../../utilities/config-provider';
+import { Primitive } from '../../internal/primitive';
+import { provideSelectGroupContext } from './context';
+
+const { as = 'div' } = defineProps<SelectGroupProps>();
+const { forwardRef } = useForwardExpose();
+
+const groupId = useId(undefined, 'select-group');
+
+provideSelectGroupContext({ id: groupId });
+</script>
+
+<template>
+  <Primitive
+    :ref="forwardRef"
+    :as="as"
+    role="group"
+    :aria-labelledby="groupId"
+  >
+    <slot />
+  </Primitive>
+</template>