fix: doctor can see patient-created follow-ups, camelCase JSON support

- FollowUpService: doctor query includes unassigned (DoctorId=null) follow-ups
- FollowUpController: doctor creates follow-up with correct patientId and sets DoctorId
- FollowUpCreateRequest/UpdateRequest: changed from positional record to class for System.Text.Json compat
- Program.cs: added PropertyNameCaseInsensitive for camelCase JSON deserialization

backend/src/HealthManager.WebApi/Controllers/FollowUpController.cs

@@ -45,8 +45,17 @@ public class FollowUpController(FollowUpService followUpService) : ControllerBas
     [HttpPost]
     public async Task<IActionResult> AddFollowUp([FromBody] FollowUpCreateRequest request)
     {
-        var followUp = await followUpService.AddAsync(UserId, request.Title, request.Description,
-            request.ScheduledAt, request.ReminderEnabled);
+        var patientId = UserId;
+        Guid? doctorId = null;
+
+        if (Role == "doctor" && request.PatientId.HasValue)
+        {
+            patientId = request.PatientId.Value;
+            doctorId = UserId;
+        }
+
+        var followUp = await followUpService.AddAsync(patientId, request.Title, request.Description,
+            request.ScheduledAt, request.ReminderEnabled, doctorId);
         return Ok(new { followUp.Id, followUp.Title, followUp.Status });
     }
 
@@ -61,7 +70,20 @@ public class FollowUpController(FollowUpService followUpService) : ControllerBas
     }
 }
 
-public record FollowUpCreateRequest(string Title, string? Description, DateTime ScheduledAt, bool ReminderEnabled = true);
+public class FollowUpCreateRequest
+{
+    public string Title { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public DateTime ScheduledAt { get; set; }
+    public bool ReminderEnabled { get; set; } = true;
+    public Guid? PatientId { get; set; }
+}
 
-public record FollowUpUpdateRequest(
-    string? Title, string? Description, DateTime? ScheduledAt, string? Status, string? Notes);
+public class FollowUpUpdateRequest
+{
+    public string? Title { get; set; }
+    public string? Description { get; set; }
+    public DateTime? ScheduledAt { get; set; }
+    public string? Status { get; set; }
+    public string? Notes { get; set; }
+}

backend/src/HealthManager.WebApi/Program.cs

@@ -74,7 +74,11 @@ builder.Services.AddCors(options =>
     });
 });
 
-builder.Services.AddControllers();
+builder.Services.AddControllers()
+    .AddJsonOptions(options =>
+    {
+        options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
+    });
 
 var app = builder.Build();