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/SelectContent.vue

@@ -0,0 +1,74 @@
+<script lang="ts">
+import type { SelectContentImplEmits, SelectContentImplProps } from './SelectContentImpl.vue';
+
+/**
+ * The floating panel that holds the options. While open it mounts
+ * `SelectContentImpl` behind `Presence` (so it can animate in and out); while
+ * closed it still renders the options into a detached `DocumentFragment` so each
+ * `SelectItem` registers its value/label and `SelectValue` shows the
+ * initially-selected label before the dropdown is ever opened. Usually placed
+ * inside a `SelectPortal` and contains a `SelectViewport` of `SelectItem`s.
+ */
+export interface SelectContentProps extends SelectContentImplProps {
+  /**
+   * Force mounting (keeps the panel in the DOM) for externally-controlled
+   * animation libraries.
+   */
+  forceMount?: boolean;
+}
+
+export type SelectContentEmits = SelectContentImplEmits;
+</script>
+
+<script setup lang="ts">
+import { computed, onMounted, ref, shallowRef, watch } from 'vue';
+
+import { Presence } from '../../utilities/presence';
+import { useSelectRootContext } from './context';
+import SelectContentImpl from './SelectContentImpl.vue';
+import SelectProvider from './SelectProvider.vue';
+
+const props = defineProps<SelectContentProps>();
+const emit = defineEmits<SelectContentEmits>();
+const rootCtx = useSelectRootContext();
+
+const present = computed(() => props.forceMount || rootCtx.open.value);
+
+// Delay toggling render-presence so children re-render with the latest state
+// before the exit transition runs (state-based `data-state=closed` animations).
+const renderPresence = ref(present.value);
+function syncRenderPresence() {
+  renderPresence.value = present.value;
+}
+watch(present, () => {
+  setTimeout(syncRenderPresence);
+});
+
+// Detached fragment that keeps options mounted (and registered) while closed.
+const fragment = shallowRef<DocumentFragment | undefined>(undefined);
+onMounted(() => {
+  fragment.value = typeof DocumentFragment !== 'undefined' ? new DocumentFragment() : undefined;
+});
+</script>
+
+<template>
+  <Presence
+    v-if="present || renderPresence"
+    :present="present"
+  >
+    <SelectContentImpl
+      v-bind="props"
+      @close-auto-focus="emit('closeAutoFocus', $event)"
+      @escape-key-down="emit('escapeKeyDown', $event)"
+      @pointer-down-outside="emit('pointerDownOutside', $event)"
+    >
+      <slot />
+    </SelectContentImpl>
+  </Presence>
+
+  <Teleport v-else-if="fragment" :to="fragment">
+    <SelectProvider :context="rootCtx">
+      <slot />
+    </SelectProvider>
+  </Teleport>
+</template>