fix(canvas): 智能体面板 - 修复交互失效与布局异常 (#152)

- 为 motion.aside 补充 pointer-events-auto，恢复面板内输入框、按钮等交互
- section 启用 flex 垂直布局并修正 paddingRight 条件，避免面板跑到下方
- PANEL_SLOT_TOP_OFFSET 从 288 调整为 80，移除活动任务面板不必要的预留空间

Closes #151

Co-authored-by: sikongyue <3155157671@qq.com>

web/src/pages/canvas/project.tsx

@@ -1383,9 +1383,9 @@ function InfiniteCanvasPage() {
         <main id="canvas-main" tabIndex={-1} className="flex h-full min-h-0 overflow-hidden outline-none" style={{ background: theme.canvas.background, color: theme.node.text }}>
             {shortDramaEnabled && currentProject?.projectId ? <CanvasProjectSidebar projectId={currentProject.projectId} detail={linkedProjectQuery.data} onAddChapter={handleProjectChapterInsert} onLocateStyle={locateProjectStyleNode} onOpenAssets={() => openProjectAssets()} /> : null}
             <section
-                className="relative min-w-0 flex-1 overflow-hidden transition-[padding]"
+                className="relative min-w-0 flex-1 flex flex-col min-h-0 overflow-hidden transition-[padding]"
                 style={{
-                    paddingRight: focusMode && anyPanelOpen ? panelColumnWidth : undefined,
+                    paddingRight: anyPanelOpen ? panelColumnWidth : undefined,
                 }}
             >
                 <CanvasTopBar
@@ -1449,6 +1449,7 @@ function InfiniteCanvasPage() {
 
                 <CanvasStylePickerModal open={stylePickerOpen} value={activeStylePresetId} onClose={() => setStylePickerOpen(false)} onSelect={selectCanvasStyle} />
 
+                <div className="relative flex-1 min-h-0">
                 <InfiniteCanvas
                     containerRef={containerRef}
                     viewport={viewport}
@@ -1541,6 +1542,7 @@ function InfiniteCanvasPage() {
                         onOpenDrawing={openDrawingNode}
                     />
                 </InfiniteCanvas>
+                </div>
 
                 {angleNode?.metadata?.content ? (
                     <CanvasNodePanelOverlay node={angleNode} viewport={viewport} containerRef={containerRef} panelWidth={580} panelHeight={350}>