fix: 🐛 [App Feedback] under Status column, the Completed text shows splitted...

[yhay81]

Fixes #188.

Summary

🐛 [App Feedback] under Status column, the Completed text shows splitted apart in seprate lines

Validation

• Mechanical gate: +4/-2, tests passed
• Adversarial review: approved

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🤖 AI-authored PR, operated by @yhay81.

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[zerx-lab]

感谢贡献！这个修复的意图是对的，但 main 上的任务列表列宽体系已重构为列注册表（lib/src/widgets/task_columns.dart 的 kTaskColumns，表头/行/宽度预算共用单一事实源），本 PR 修改的硬编码列宽代码已不存在，产生冲突无法直接合并。

现状说明：

• 换行问题（Completed 被拆成两行）已在重构中修复：状态单元格带 maxLines: 1 + TextOverflow.ellipsis；
• 本 PR 的状态列 60→80 加宽仍有价值（新单元格含状态图标，英文 Completed 在 60px 下会被省略），已在新体系中等价落地。

故关闭本 PR，修复效果等价保留。