refactor: 4层架构重构 + 饮食VLM接入 + 多项修复

- 后端: remaining_endpoints拆分为6个独立文件
- 后端: AI Agent Handler从ai_chat_endpoints抽取为7个独立处理器
- 后端: 食物识别prompt改为输出结构化JSON
- 前端: 饮食识别从Mock替换为真实VLM API调用
- 前端: 首页图片上传URL修复(/api/upload→/api/files/upload)
- 前端: 拍饮食按钮导航到独立DietCapturePage
- 前端: 删除无用agent_bar.dart
- 前端: 修复widget_test.dart过期属性名
- 前端: 恢复ServicePackageCard和详情页
- 新增6份实施文档(情况/问诊/报告/建档/日历/视觉统一)

backend/src/Health.WebApi/Endpoints/report_endpoints.cs

@@ -0,0 +1,26 @@
+namespace Health.WebApi.Endpoints;
+
+public static class ReportEndpoints
+{
+    public static void MapReportEndpoints(this WebApplication app)
+    {
+        var group = app.MapGroup("/api/reports").RequireAuthorization();
+
+        group.MapGet("/", async (HttpContext http, AppDbContext db, CancellationToken ct) =>
+        {
+            var userId = GetUserId(http);
+            var reports = await db.Reports.Where(r => r.UserId == userId).OrderByDescending(r => r.CreatedAt).ToListAsync(ct);
+            return Results.Ok(new { code = 0, data = reports, message = (string?)null });
+        });
+
+        group.MapGet("/{id:guid}", async (Guid id, HttpContext http, AppDbContext db, CancellationToken ct) =>
+        {
+            var userId = GetUserId(http);
+            var report = await db.Reports.FirstOrDefaultAsync(r => r.Id == id && r.UserId == userId, ct);
+            return report == null ? Results.Ok(new { code = 40004, message = "不存在" }) : Results.Ok(new { code = 0, data = report, message = (string?)null });
+        });
+    }
+
+    private static Guid GetUserId(HttpContext http) =>
+        Guid.TryParse(http.User.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value, out var id) ? id : Guid.Empty;
+}