合并 master 的滑动条样式改造

音效面板跟随 master 从 form 提交改为按钮 onClick，保留 canonical soundEffectDialog 与 canGenerate 守卫。

音效锁定态断言改读 aria-readonly，适配 AutoGrowTextArea 改用 Lexical contentEditable。

src/index.css

@@ -6828,13 +6828,13 @@ html[data-mobile-keyboard-open='true'] .platform-mobile-bottom-dock {
 }
 
 .image-canvas-editor__generation-prompt {
+  --auto-grow-editor-radius: 1.05rem;
+  --auto-grow-editor-min-height: 3.35rem;
+  --auto-grow-editor-padding: 0.52rem 0.82rem;
   grid-column: 1 / -1;
-  min-height: 3.35rem;
-  resize: none;
   border: 1px solid rgba(15, 23, 42, 0.08);
-  border-radius: 1.05rem;
+  border-radius: var(--auto-grow-editor-radius);
   background: #f8fafc;
-  padding: 0.52rem 0.82rem;
   color: #0f172a;
   font: inherit;
   font-size: 0.82rem;
@@ -6843,23 +6843,27 @@ html[data-mobile-keyboard-open='true'] .platform-mobile-bottom-dock {
   outline: none;
 }
 
-.image-canvas-editor__generation-prompt:focus,
+.image-canvas-editor__generation-prompt:focus-within,
 .image-canvas-editor__video-prompt:focus {
   border-color: var(--image-canvas-brand-border-strong);
   background: #ffffff;
   box-shadow: 0 0 0 3px var(--image-canvas-brand-focus-ring);
 }
 
-.image-canvas-editor__generation-prompt::placeholder {
+.image-canvas-editor__generation-prompt .auto-grow-text-area__placeholder {
   color: #94a3b8;
 }
 
-.image-canvas-editor__generation-prompt[aria-invalid='true'] {
+.image-canvas-editor__generation-prompt:has(
+    .auto-grow-text-area__content[aria-invalid='true']
+  ) {
   border-color: #e11d48;
   background: #fff7f8;
 }
 
-.image-canvas-editor__generation-prompt[aria-invalid='true']:focus {
+.image-canvas-editor__generation-prompt:has(
+    .auto-grow-text-area__content[aria-invalid='true']
+  ):focus-within {
   border-color: #e11d48;
   box-shadow: 0 0 0 3px rgba(225, 29, 72, 0.14);
 }
@@ -6886,7 +6890,9 @@ html[data-mobile-keyboard-open='true'] .platform-mobile-bottom-dock {
 .image-canvas-editor__generation-composer-footer {
   grid-column: 1 / -1;
   display: grid;
-  grid-template-columns: max-content minmax(0, 1fr) max-content max-content max-content;
+  grid-template-columns:
+    max-content minmax(0, 1fr)
+    max-content max-content max-content;
   align-items: center;
   gap: 0.1rem;
   justify-content: start;
@@ -7676,8 +7682,8 @@ button.image-canvas-editor__reference-chip:disabled {
 
 .image-canvas-editor__character-composer
   .image-canvas-editor__generation-prompt {
-  min-height: 5.1rem;
-  padding-top: 0.42rem;
+  --auto-grow-editor-min-height: 5.1rem;
+  --auto-grow-editor-padding: 0.42rem 0.82rem 0.52rem;
 }
 
 .image-canvas-editor__character-composer
@@ -7725,7 +7731,7 @@ button.image-canvas-editor__reference-chip:disabled {
 }
 
 .image-canvas-editor__publication-description {
-  min-height: 4rem;
+  --auto-grow-editor-min-height: 4rem;
 }
 
 .image-canvas-editor__publication-composer
@@ -7762,8 +7768,8 @@ button.image-canvas-editor__reference-chip:disabled {
 }
 
 .image-canvas-editor__icon-composer .image-canvas-editor__generation-prompt {
-  min-height: 5.1rem;
-  padding-top: 0.42rem;
+  --auto-grow-editor-min-height: 5.1rem;
+  --auto-grow-editor-padding: 0.42rem 0.82rem 0.52rem;
 }
 
 .image-canvas-editor__character-composer
@@ -8036,11 +8042,7 @@ button.image-canvas-editor__reference-chip:disabled {
 }
 
 .image-canvas-editor__spec-textarea {
-  min-height: 3.8rem;
-}
-
-.image-canvas-editor__spec-textarea::placeholder {
-  color: #94a3b8;
+  --auto-grow-editor-min-height: 3.8rem;
 }
 
 .image-canvas-editor__spec-textarea--view {
@@ -8621,7 +8623,7 @@ button.image-canvas-editor__reference-chip:disabled {
 }
 
 .image-canvas-editor__quick-edit-prompt {
-  min-height: 5.6rem;
+  --auto-grow-editor-min-height: 5.6rem;
 }
 
 .image-canvas-editor__quick-edit-controls {
@@ -8771,7 +8773,8 @@ button.image-canvas-editor__reference-chip:disabled {
 
 .image-canvas-editor__character-animation-textarea {
   grid-column: 1 / -1;
-  min-height: 8rem;
+  --auto-grow-editor-min-height: 8rem;
+  --auto-grow-editor-max-height: 16rem;
 }
 
 .image-canvas-editor__character-animation-presets {
@@ -8863,12 +8866,12 @@ button.image-canvas-editor__reference-chip:disabled {
 }
 
 .image-canvas-editor__generate-prompt {
-  min-height: 7rem;
-  resize: none;
+  --auto-grow-editor-radius: 0.45rem;
+  --auto-grow-editor-min-height: 7rem;
+  --auto-grow-editor-padding: 0.7rem;
   border: 1px solid #d9dee8;
-  border-radius: 0.45rem;
+  border-radius: var(--auto-grow-editor-radius);
   background: #f8fafc;
-  padding: 0.7rem;
   color: #1f2937;
   font: inherit;
   font-size: 0.82rem;
@@ -8876,7 +8879,7 @@ button.image-canvas-editor__reference-chip:disabled {
   outline: none;
 }
 
-.image-canvas-editor__generate-prompt:focus {
+.image-canvas-editor__generate-prompt:focus-within {
   border-color: var(--image-canvas-brand-border-strong);
   background: #ffffff;
   box-shadow: 0 0 0 3px var(--image-canvas-brand-focus-ring);
@@ -16878,28 +16881,128 @@ button {
 }
 
 .auto-grow-text-area {
-  scrollbar-color: #cbd5e1 transparent;
-  scrollbar-width: thin;
+  position: relative;
+  display: block;
+  box-sizing: border-box;
+  width: 100%;
+  min-width: 0;
+  min-height: var(--auto-grow-editor-min-height, 2.5rem);
+  max-height: var(--auto-grow-editor-max-height, 8rem);
+  border-radius: var(--auto-grow-editor-radius, 1rem);
+  overflow: hidden;
 }
 
-.auto-grow-text-area::-webkit-scrollbar {
-  width: 6px;
+.auto-grow-text-area__content {
+  box-sizing: border-box;
+  width: 100%;
+  min-height: calc(var(--auto-grow-editor-min-height, 2.5rem) - 2px);
+  padding: var(--auto-grow-editor-padding, 0.5rem 0.75rem);
+  padding-right: 2.25rem;
+  outline: none;
+  overflow-wrap: anywhere;
+  white-space: pre-wrap;
+  -webkit-user-select: text;
+  user-select: text;
 }
 
-.auto-grow-text-area::-webkit-scrollbar-track {
-  margin-block: 10px;
-  background-color: transparent;
+.auto-grow-text-area__placeholder {
+  position: absolute;
+  inset: 0;
+  box-sizing: border-box;
+  padding: var(--auto-grow-editor-padding, 0.5rem 0.75rem);
+  padding-right: 2.25rem;
+  overflow: hidden;
+  color: #94a3b8;
+  pointer-events: none;
+  text-overflow: ellipsis;
+  white-space: nowrap;
 }
 
-.auto-grow-text-area::-webkit-scrollbar-thumb {
-  border: 1px solid transparent;
+.auto-grow-text-area__viewport,
+.auto-grow-text-area [data-overlayscrollbars-viewport] {
+  /* 独立 viewport 不随内容增高，达到上限后只由它承接滚动。 */
+  display: block;
+  height: 100%;
+  min-height: 0;
+  overflow-x: hidden !important;
+  overflow-y: auto !important;
+  overscroll-behavior: contain;
+}
+
+.auto-grow-text-area__content-root {
+  box-sizing: border-box;
+  min-height: calc(var(--auto-grow-editor-min-height, 2.5rem) - 2px);
+}
+
+.auto-grow-text-area[data-disabled='true'] {
+  cursor: not-allowed;
+  opacity: 0.6;
+}
+
+.auto-grow-text-area[data-readonly='true'] {
+  cursor: default;
+}
+
+.editor-agent-conversation__draft-input {
+  --auto-grow-editor-radius: 1.5rem;
+  --auto-grow-editor-padding: 0.5rem 0.75rem;
+  border-radius: var(--auto-grow-editor-radius);
+}
+
+/* 微信式编辑器滚动条：轨道透明，8px 胶囊滑块内缩于输入框圆角之内。 */
+.auto-grow-text-area
+  > .os-theme-auto-grow-text-area.os-scrollbar-vertical.os-scrollbar-cornerless {
+  --os-size: 8px;
+  --os-padding-axis: 0;
+  --os-padding-perpendicular: 0;
+  --os-track-border-radius: 999px;
+  --os-track-bg: transparent;
+  --os-track-bg-hover: transparent;
+  --os-track-bg-active: transparent;
+  --os-handle-border-radius: 999px;
+  --os-handle-bg: rgba(98, 98, 98, 0.56);
+  --os-handle-bg-hover: rgba(98, 98, 98, 0.72);
+  --os-handle-bg-active: rgba(98, 98, 98, 0.86);
+  --os-handle-min-size: 24px;
+  --os-handle-perpendicular-size: 100%;
+  --os-handle-perpendicular-size-hover: 100%;
+  --os-handle-perpendicular-size-active: 100%;
+  box-sizing: border-box;
+  top: var(--auto-grow-editor-radius, 1rem) !important;
+  right: 5px;
+  bottom: var(--auto-grow-editor-radius, 1rem) !important;
+  width: 8px;
+  padding: 0;
+}
+
+.auto-grow-text-area
+  > .os-theme-auto-grow-text-area.os-scrollbar-vertical
+  .os-scrollbar-track {
+  width: 8px;
   border-radius: 999px;
-  background-color: #cbd5e1;
-  background-clip: padding-box;
+  background: transparent;
 }
 
-.auto-grow-text-area::-webkit-scrollbar-thumb:hover {
-  background-color: #94a3b8;
+.auto-grow-text-area
+  > .os-theme-auto-grow-text-area.os-scrollbar-vertical
+  .os-scrollbar-handle {
+  width: 8px;
+  min-height: 24px;
+  border: 0;
+  border-radius: 999px;
+  background: rgba(98, 98, 98, 0.56);
+}
+
+.auto-grow-text-area
+  > .os-theme-auto-grow-text-area.os-scrollbar-vertical:hover
+  .os-scrollbar-handle {
+  background: rgba(98, 98, 98, 0.72);
+}
+
+.auto-grow-text-area
+  > .os-theme-auto-grow-text-area.os-scrollbar-vertical:active
+  .os-scrollbar-handle {
+  background: rgba(98, 98, 98, 0.86);
 }
 
 .image-canvas-editor__metadata-dialog.platform-modal-shell {