Fix DNS resolution: Add fallback DNS for external domains

Problem:
- When --accept-dns=true is used, MagicDNS (100.100.100.100) becomes
  the only DNS resolver for systemd-resolved
- If MagicDNS fails to forward external queries, domains like
  google.com become unreachable
- This commonly occurs due to network latency or connectivity issues

Solution:
- Add configure_dns_fallback() function to quick-install.sh
- Create /etc/systemd/resolved.conf.d/headscale-fallback.conf
- Set FallbackDNS to 1.1.1.1, 8.8.8.8, 168.126.63.1 (Korea DNS)
- Add external DNS verification test in verify_connection()
- Support non-systemd systems via /etc/resolv.conf modification

Result:
- MagicDNS continues to work for *.headscale.local internal domains
- External domains resolve via fallback DNS when MagicDNS fails
- Installation script verifies DNS resolution before completion

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

farmq-admin/app.py

@@ -415,22 +415,23 @@ def create_app(config_name=None):
             # FARMQ 데이터베이스에 약국 생성
             farmq_session = get_farmq_session()
             try:
-                # pharmacy_code 자동 생성 (P001~P999)
-                last_pharmacy = farmq_session.query(PharmacyInfo)\
+                # pharmacy_code 자동 생성 (P0001~P9999)
+                # P + 4자리 숫자 형식만 필터링
+                all_pharmacies = farmq_session.query(PharmacyInfo)\
                     .filter(PharmacyInfo.pharmacy_code.like('P%'))\
-                    .order_by(PharmacyInfo.pharmacy_code.desc())\
-                    .first()
+                    .all()
 
-                if last_pharmacy and last_pharmacy.pharmacy_code:
-                    try:
-                        last_num = int(last_pharmacy.pharmacy_code[1:])
-                        new_num = last_num + 1
-                    except:
-                        new_num = 1
-                else:
-                    new_num = 1
+                max_num = 0
+                for pharmacy in all_pharmacies:
+                    code = pharmacy.pharmacy_code
+                    # P + 정확히 4자리 숫자 형식만 체크 (P0001, P0002, P0003...)
+                    if code and len(code) == 5 and code[0] == 'P' and code[1:].isdigit():
+                        num = int(code[1:])
+                        if num > max_num:
+                            max_num = num
 
-                pharmacy_code = f"P{new_num:03d}"  # P001, P002, ...
+                new_num = max_num + 1
+                pharmacy_code = f"P{new_num:04d}"  # P0001, P0002, ...
 
                 new_pharmacy = PharmacyInfo(
                     pharmacy_code=pharmacy_code,
@@ -445,9 +446,11 @@ def create_app(config_name=None):
                     owner_license=data.get('owner_license', '').strip(),
                     owner_phone=data.get('owner_phone', '').strip(),
                     owner_email=data.get('owner_email', '').strip(),
-                    institution_code=data.get('institution_code', '').strip() or None,
+                    # 요양기관부호: hira_code 우선, 없으면 institution_code 사용
+                    institution_code=(data.get('hira_code', '').strip() or data.get('institution_code', '').strip()) or None,
                     institution_type=data.get('institution_type', '').strip() or None,
                     api_port=data.get('api_port', 8082),
+                    tailscale_ip=data.get('vpn_ip', '').strip() or None,  # VPN IP (선택)
 
                     # 기존 필드
                     proxmox_host=data.get('proxmox_host', '').strip(),