refactor: gate DOM probes behind IN_BROWSER

PHILOSOPHY §2.10 — four sites across useHotkey, useClickOutside,
createCombobox, and SelectRoot. Returns false/null under SSR; all
consumers handle those values cleanly.

Author: johnleider

packages/0/src/components/Select/SelectRoot.vue

@@ -11,6 +11,9 @@
  */
 
 <script lang="ts">
+  // Globals
+  import { IN_BROWSER } from '#v0/constants/globals'
+
   // Components
   import { Atom } from '#v0/components/Atom'
   import SelectHiddenInput from './SelectHiddenInput.vue'
@@ -158,7 +161,7 @@
   const virtualFocus = useVirtualFocus(
     () => selection.values().map(ticket => ({
       id: ticket.id,
-      el: () => document.querySelector<HTMLElement>(`#${CSS.escape(`${id}-option-${ticket.id}`)}`),
+      el: () => IN_BROWSER ? document.querySelector<HTMLElement>(`#${CSS.escape(`${id}-option-${ticket.id}`)}`) : null,
       disabled: ticket.disabled,
     })),
     {

packages/0/src/composables/createCombobox/index.ts

@@ -27,6 +27,9 @@
  * ```
  */
 
+// Globals
+import { IN_BROWSER } from '#v0/constants/globals'
+
 // Composables
 import { useContext } from '#v0/composables/createContext'
 import { createSelection } from '#v0/composables/createSelection'
@@ -194,7 +197,7 @@ export function createCombobox (options: ComboboxOptions = {}): ComboboxContext
       .filter(ticket => filtered.value.has(ticket.id) && !toValue(ticket.disabled))
       .map(ticket => ({
         id: ticket.id,
-        el: () => document.querySelector<HTMLElement>(`#${CSS.escape(`${id}-option-${ticket.id}`)}`),
+        el: () => IN_BROWSER ? document.querySelector<HTMLElement>(`#${CSS.escape(`${id}-option-${ticket.id}`)}`) : null,
         disabled: ticket.disabled,
       })),
     {

packages/0/src/composables/useClickOutside/index.ts

@@ -31,6 +31,9 @@
  * ```
  */
 
+// Globals
+import { IN_BROWSER } from '#v0/constants/globals'
+
 // Composables
 import {
   useDocumentEventListener,
@@ -349,6 +352,7 @@ export function useClickOutside (
    * Handle window blur - detect focus moving to iframe.
    */
   function onBlur (event: FocusEvent) {
+    if (!IN_BROWSER) return
     if (isPaused.value) return
     if (event.defaultPrevented) return
 

packages/0/src/composables/useHotkey/index.ts

@@ -162,6 +162,7 @@ export function useHotkey (
   let groupIndex = 0
 
   function isInputFocused (): boolean {
+    if (!IN_BROWSER) return false
     if (toValue(inputs)) return false
 
     const activeElement = document.activeElement as HTMLElement | null