Fix Prompt Builder Nitro build by inlining sequence helpers in utils.

The relative re-export of shared/prompt-sequences.mjs left an unresolved import in the SSR bundle.

shared/prompt-sequences.mjs

@@ -1,68 +0,0 @@
-/** Pure prompt-sequence helpers (shared by page + tests). */
-
-export function newId() {
-  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
-    return crypto.randomUUID()
-  }
-  return `ps-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 10)}`
-}
-
-export function emptyCharacter() {
-  return { id: newId(), name: '', description: '' }
-}
-
-export function emptyScene(index = 1) {
-  return {
-    id: newId(),
-    title: `Scene ${Math.max(1, index)}`,
-    style: '',
-    settings: '',
-    characters: [emptyCharacter()],
-    prompt: ''
-  }
-}
-
-export function cloneSceneForNext(previous, nextIndex) {
-  return {
-    id: newId(),
-    title: `Scene ${nextIndex}`,
-    style: previous.style,
-    settings: previous.settings,
-    characters: (previous.characters || []).map(character => ({
-      id: newId(),
-      name: character.name,
-      description: character.description
-    })),
-    prompt: previous.prompt
-  }
-}
-
-export function formatCharacterLine(character) {
-  const name = String(character?.name || '').trim()
-  const description = String(character?.description || '').trim()
-  if (!name && !description) return ''
-  if (name && description) return `${name}: ${description}`
-  return name || description
-}
-
-export function assembleSceneText(scene) {
-  const characterBlock = (scene?.characters || [])
-    .map(formatCharacterLine)
-    .filter(Boolean)
-    .join('\n')
-  const parts = [
-    String(scene?.style || '').trim(),
-    String(scene?.settings || '').trim(),
-    characterBlock,
-    String(scene?.prompt || '').trim()
-  ].filter(Boolean)
-  return parts.join('\n\n')
-}
-
-/** Scenes join with \\n\\n\\n (desktop Batch double blank). Name is never included. */
-export function assembleSequenceText(sequence) {
-  return (sequence?.scenes || [])
-    .map(assembleSceneText)
-    .filter(Boolean)
-    .join('\n\n\n')
-}