fix(project): 项目名称改为可重复展示名

[xyh202131]

Summary

• 项目名称只作为展示字段，稳定身份继续使用项目 ID
• 创建和重命名项目时允许同名，不再自动追加序号
• 增加迁移以移除用户与项目名称的唯一约束

Verification

• 后端项目与 Schema 测试（35 passed）
• 前端项目创建测试（13 passed）
• Ruff、TypeScript、lint、生产构建通过

Refs #783

[vercel]

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Project	Deployment	Actions	Updated (UTC)
windup	Ready	Preview	Aug 28, 2026 7:47pm

[github-actions]

⚠️ @xyh202131，此 PR 尚未关联 issue。请在 PR 描述中使用 Closes #123 等关闭关键字；更新描述后，此提醒将自动标记为已解决。

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #912      +/-   ##
==========================================
- Coverage   86.50%   86.21%   -0.29%     
==========================================
  Files         304      305       +1     
  Lines       23830    23787      -43     
  Branches     3597     3601       +4     
==========================================
- Hits        20615    20509     -106     
- Misses       2249     2318      +69     
+ Partials      966      960       -6     

Flag	Coverage Δ
backend	91.26% <100.00%> (+<0.01%)	⬆️
frontend	80.01% <ø> (-0.63%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ges/app/src/windup_app/server/project/interface.py	95.00% <ø> (-0.46%)	⬇️
...ackages/app/src/windup_app/server/project/model.py	100.00% <100.00%> (ø)
...ckages/app/src/windup_app/server/project/naming.py	100.00% <ø> (ø)
...kages/app/src/windup_app/server/project/service.py	97.18% <ø> (-0.12%)	⬇️
...end/packages/app/src/windup_app/web/api/project.py	94.36% <100.00%> (+1.62%)	⬆️
frontend/src/pages/project-create/index.tsx	96.15% <ø> (ø)

... and 5 files with indirect coverage changes

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[fennoai]

审阅了项目展示名改为可重复后的完整变更，覆盖 ORM 约束、创建/重命名 API、迁移脚本、前端文案及相关回归测试。项目 ID 仍作为详情、列表和关联路径的稳定标识，创建与重命名的同名行为与新的数据库约束保持一致；未发现达到报告阈值的正确性、性能或安全问题。

验证：PR 的 lint-and-test、Frontend checks、gate 和 Vercel 检查均通过；本地静态检查（git diff --check、Python 编译）通过。当前环境未安装 uv 或 pytest，因此未重复运行 Python 测试。