feat: doctor reply + diagnosis + tracking code per health request

Backend:
- HealthRequest model: TrackingCode (DR-XXXXXX), Diagnosis,
  DoctorReply, RepliedAt fields
- Runtime migration: ALTER TABLE adds 4 new columns to existing DB
- POST /api/health-request: auto-generates tracking code, returns it
- PUT /api/health-requests/{id}/reply: doctor sets diagnosis + reply
- GET /api/health-request/track/{code}: public lookup by tracking code
- GET /api/health-requests?phone=: filter history by phone number

Admin panel:
- Request table shows tracking code column (gold badge)
- Detail modal (680px): tracking code header, patient info, full message
- Previous doctor reply shown in green box if exists
- Reply form: diagnosis input + textarea for doctor message
- History panel: all requests from same phone, click to switch
- 'پاسخ / مشاهده' button opens reply modal directly

Frontend:
- After form submit: shows tracking code in green box to user
  (format: DR-XXXXXX, stays visible 8 seconds)
- Box auto-hides and form resets after timeout

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

DrSousan.Api/Pages/Index.cshtml

@@ -791,6 +791,7 @@
           </div>
           <button type="submit" class="form-submit" id="booking-submit">ارسال و رزرو نوبت</button>
         </form>
+        <div id="booking-tracking" style="display:none"></div>
       </div>
     </div>
   </div>
@@ -844,15 +845,30 @@
         })
       });
       if (!res.ok) throw new Error();
-      btn.textContent = '✓ درخواست شما ثبت شد';
+      const data = await res.json();
+      const code = data.trackingCode || '';
+      btn.textContent = '✓ درخواست ثبت شد';
       btn.style.background = '#2D7A4F';
+      // Show tracking code to user
+      const trackBox = document.getElementById('booking-tracking');
+      if (trackBox && code) {
+        trackBox.innerHTML = `
+          <div style="background:#E8F5E9;border-radius:14px;padding:1rem 1.4rem;border-right:4px solid #388E3C;margin-top:1rem">
+            <p style="font-size:.85rem;color:#2D7A4F;margin-bottom:.4rem;font-weight:600">✓ درخواست شما با موفقیت ثبت شد</p>
+            <p style="font-size:.82rem;color:#555;margin-bottom:.5rem">کد رهگیری شما برای پیگیری پاسخ پزشک:</p>
+            <div style="font-size:1.3rem;font-weight:700;letter-spacing:.1em;color:#1a1a1a;font-family:monospace;background:#fff;display:inline-block;padding:.3rem .8rem;border-radius:8px;border:1.5px solid #a5d6a7">${code}</div>
+            <p style="font-size:.75rem;color:#777;margin-top:.5rem">این کد را نزد خود نگه دارید. در اسرع وقت با شما تماس می‌گیریم.</p>
+          </div>`;
+        trackBox.style.display = 'block';
+      }
       setTimeout(() => {
         btn.textContent = 'ارسال و رزرو نوبت';
         btn.style.background = '';
         btn.disabled = false;
         e.target.reset();
         document.getElementById('booking-category').value = 'beauty';
-      }, 3500);
+        if (trackBox) { trackBox.innerHTML=''; trackBox.style.display='none'; }
+      }, 8000);
     } catch {
       btn.textContent = 'خطا — دوباره تلاش کنید';
       btn.style.background = '#c62828';