Migrate from file-based configs to database with per-IP site configuration

Major architectural changes:
   - Replace YAML config files with database-stored ScanConfig model
   - Remove CIDR block support in favor of individual IP addresses per site
   - Each IP now has its own expected_ping, expected_tcp_ports, expected_udp_ports
   - AlertRule now uses config_id FK instead of config_file string

   API changes:
   - POST /api/scans now requires config_id instead of config_file
   - Alert rules API uses config_id with validation
   - All config dropdowns fetch from /api/configs dynamically

   Template updates:
   - scans.html, dashboard.html, alert_rules.html load configs via API
   - Display format: Config Title (X sites) in dropdowns
   - Removed Jinja2 config_files loops

   Migrations:
   - 008: Expand CIDRs to individual IPs with per-IP port configs
   - 009: Remove CIDR-related columns
   - 010: Add config_id to alert_rules, remove config_file

app/web/api/configs.py

@@ -174,7 +174,7 @@ def get_config(config_id: int):
                     "id": 1,
                     "name": "Production DC",
                     "description": "...",
-                    "cidr_count": 5
+                    "ip_count": 5
                 }
             ],
             "created_at": "2025-11-19T10:30:00Z",