Group extension chains in the library and add shot-script queues.

Keep every saved segment, show the longest clip with an expand list, branch on extend, and parse shot 2/3 blocks into a shared-duration queue with live part status.

utils/parseShots.ts

@@ -0,0 +1,43 @@
+export interface ParsedShot {
+  n: number
+  prompt: string
+  role: 'initial' | 'extension'
+}
+
+export function parseShotScript(text: string): ParsedShot[] {
+  const src = String(text || '').replace(/\r\n/g, '\n')
+  const marker = /shot\s+(\d+)\b/gi
+  const markers: { n: number; start: number; end: number }[] = []
+  for (const match of src.matchAll(marker)) {
+    markers.push({
+      n: Number(match[1]),
+      start: match.index || 0,
+      end: (match.index || 0) + match[0].length
+    })
+  }
+  const blocks: { n: number; prompt: string }[] = []
+  if (!markers.length) {
+    const prompt = src.trim()
+    return prompt ? [{ n: 1, prompt, role: 'initial' }] : []
+  }
+  const preamble = src.slice(0, markers[0].start).trim()
+  if (preamble) blocks.push({ n: 1, prompt: preamble })
+  for (let i = 0; i < markers.length; i++) {
+    const from = markers[i].end
+    const to = i + 1 < markers.length ? markers[i + 1].start : src.length
+    const prompt = src.slice(from, to).trim()
+    if (prompt) blocks.push({ n: markers[i].n, prompt })
+  }
+  const byN = new Map<number, string>()
+  for (const block of blocks) {
+    const prev = byN.get(block.n)
+    byN.set(block.n, prev ? `${prev}\n${block.prompt}` : block.prompt)
+  }
+  return [...byN.entries()]
+    .sort((a, b) => a[0] - b[0])
+    .map(([n, prompt], index) => ({
+      n,
+      prompt,
+      role: index === 0 ? 'initial' : 'extension'
+    }))
+}