feat(core/frontend): pipeline stage editor (burn-in controls) + double-submit guard & button greying

Pipeline (脚本→资产→故事板→视频→拼接):
- Stage1 render real script shots + wire 确认脚本→adopt (advance stage)
- Stage2 add person/scene AI-生成 buttons + clickable category tabs
- Stage4 auto-poll videos to completion + per-segment upload + real frame thumbnails + download
- Stage5 real timeline editor: clips undo/redo/split/copy/delete/drag-reorder/zoom,
  subtitle style + per-clip text editor, transition select (xfade preview),
  BGM upload + volume, save draft, export-with-save → shows/download final MP4
- embedded asset URLs everywhere (beat assets pagination)

UX: re-entry guard in action() (no double-submit anywhere) + greyed :disabled
styles for btn-aigen/chat-mode/pill-cta/tl-action so generate buttons visibly
disable while generating.

Also includes prior uncommitted frontend work: settings preferences/sessions/avatar,
asset delete, account/team/products pages, fonts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/frontend/src/pipeline-page.css

@@ -166,6 +166,14 @@
   .shots-empty .empty-title { font-size: 14px; font-weight: 500; color: var(--accent-black); }
   .shots-empty .empty-hint { font-size: 12px; color: var(--black-alpha-56); line-height: 1.55; max-width: 280px; font-family: var(--font-mono); letter-spacing: .02em; }
 
+  /* 镜头脚本卡(真实脚本镜头列表) */
+  .shot-card { display: flex; gap: 12px; padding: 12px 4px; border-bottom: 1px solid var(--border-faint); }
+  .shot-card:last-child { border-bottom: 0; }
+  .shot-card .shot-n { flex: 0 0 auto; width: 26px; height: 26px; border-radius: 6px; background: var(--heat-12); color: var(--heat); font-family: var(--font-mono); font-size: 12px; font-weight: 600; display: grid; place-items: center; }
+  .shot-card .shot-main { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 4px; }
+  .shot-card .shot-meta { font-family: var(--font-mono); font-size: 10.5px; color: var(--black-alpha-48); letter-spacing: .04em; text-transform: uppercase; }
+  .shot-card .shot-narration { font-size: 13px; color: var(--accent-black); line-height: 1.5; white-space: pre-wrap; word-break: break-word; }
+
   /* 对话空态三胶囊 */
   .chat-empty { padding: 28px 18px 14px; margin: auto; display: flex; flex-direction: column; align-items: center; gap: 12px; }
   .chat-empty .ce-title { font-size: 13.5px; color: var(--accent-black); font-weight: 500; }
@@ -232,6 +240,19 @@
   .asset-card-2.prod-lib-card .prod-action .btn-aigen:hover { background: #FB6E2E; box-shadow: inset 0 -2px 4px rgba(250,93,25,.24), 0 2px 4px rgba(250,93,25,.20), 0 4px 12px rgba(250,93,25,.18); transform: translateY(-1px); }
   .asset-card-2.prod-lib-card .prod-action .btn-aigen .ai-spark { width: 14px; height: 14px; flex-shrink: 0; }
 
+  /* ── 生成中统一置灰:凡 set disabled 的按钮都灰显 + 禁手势 + 去 hover/动效(设计师要求:已点击/生成中要置灰不可点)── */
+  .btn-aigen:disabled,
+  .asset-card-2.prod-lib-card .prod-action .btn-aigen:disabled { opacity: .5; cursor: not-allowed; box-shadow: none; transform: none; }
+  .btn-aigen:disabled:hover,
+  .asset-card-2.prod-lib-card .prod-action .btn-aigen:disabled:hover { background: var(--heat); box-shadow: none; transform: none; }
+  .chat-mode:disabled { opacity: .45; cursor: not-allowed; }
+  .chat-mode:disabled:hover { background: var(--surface); border-color: var(--border-faint); color: var(--accent-black); }
+  .pill-cta:disabled { opacity: .5; cursor: not-allowed; box-shadow: none; }
+  .pill-cta:disabled:hover { box-shadow: none; }
+  .tag-add:disabled { opacity: .45; cursor: not-allowed; }
+  .tl-toolbar .tl-action:disabled { opacity: .38; cursor: not-allowed; }
+  .tl-toolbar .tl-action:disabled:hover { background: transparent; border-color: transparent; color: var(--black-alpha-72); }
+
   .prompt-box { background: var(--background-base); border: 1px solid var(--border-faint); border-radius: var(--r-sm); padding: 10px 12px; font-size: 12px; color: var(--black-alpha-56); margin-top: 8px; line-height: 1.55; font-family: var(--font-mono); letter-spacing: .01em; transition: border-color var(--t-base), background var(--t-base); }
   .prompt-box[contenteditable="true"] { cursor: text; outline: none; }
   .prompt-box[contenteditable="true"]:hover { border-color: var(--heat-20); }
@@ -322,7 +343,10 @@
 
   .editor { display: grid; grid-template-columns: 1fr 280px; grid-template-rows: 1fr auto; gap: 0; height: 580px; background: var(--surface); border: 1px solid var(--border-faint); border-radius: var(--r-md); }
   .editor-preview { padding: 16px; border-right: 1px solid var(--border-faint); border-bottom: 1px solid var(--border-faint); display: flex; flex-direction: column; gap: 12px; }
-  .editor-preview .canvas { flex: 1 1 0; min-height: 0; aspect-ratio: 9/16; margin: 0 auto; background: repeating-linear-gradient(135deg, rgba(0,0,0,0.03) 0 1px, transparent 1px 12px), var(--background-lighter); border: 1px solid var(--border-faint); border-radius: var(--r-md); display: grid; place-items: center; color: var(--black-alpha-48); font-family: var(--font-mono); font-size: 12px; }
+  .editor-preview .canvas { position: relative; overflow: hidden; flex: 1 1 0; min-height: 0; aspect-ratio: 9/16; margin: 0 auto; background: repeating-linear-gradient(135deg, rgba(0,0,0,0.03) 0 1px, transparent 1px 12px), var(--background-lighter); border: 1px solid var(--border-faint); border-radius: var(--r-md); display: grid; place-items: center; color: var(--black-alpha-48); font-family: var(--font-mono); font-size: 12px; }
+  /* 转场实时预览:切片段时画面淡场(导出才是真 xfade) */
+  .editor-preview .canvas .ed-xfade-flash { position: absolute; inset: 0; z-index: 3; background: #000; pointer-events: none; animation: edXfadeFlash 0.45s ease forwards; }
+  @keyframes edXfadeFlash { from { opacity: 0.72; } to { opacity: 0; } }
   .editor-preview .controls { display: flex; align-items: center; gap: 8px; justify-content: center; }
   .ctl-btn { width: 36px; height: 36px; border: 1px solid var(--border-faint); background: var(--surface); color: var(--black-alpha-56); border-radius: var(--r-md); display: grid; place-items: center; cursor: pointer; transition: background var(--t-base), border-color var(--t-base), color var(--t-base); }
   .ctl-btn:hover { color: var(--heat); border-color: var(--heat-40); background: var(--heat-12); }