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/templates/configs.html

@@ -295,7 +295,7 @@ function renderSitesCheckboxes(selectedIds = [], isEditMode = false) {
                        id="${prefix}-${site.id}" ${isChecked ? 'checked' : ''}>
                 <label class="form-check-label" for="${prefix}-${site.id}">
                     ${escapeHtml(site.name)}
-                    <small class="text-muted">(${site.cidr_count || 0} CIDR${site.cidr_count !== 1 ? 's' : ''})</small>
+                    <small class="text-muted">(${site.ip_count || 0} IP${site.ip_count !== 1 ? 's' : ''})</small>
                 </label>
             </div>
         `;
@@ -451,7 +451,7 @@ async function viewConfig(id) {
                 <strong>Sites (${config.site_count}):</strong>
                 <ul class="mt-2">
                     ${config.sites.map(site => `
-                        <li>${escapeHtml(site.name)} <small class="text-muted">(${site.cidr_count} CIDR${site.cidr_count !== 1 ? 's' : ''})</small></li>
+                        <li>${escapeHtml(site.name)} <small class="text-muted">(${site.ip_count} IP${site.ip_count !== 1 ? 's' : ''})</small></li>
                     `).join('')}
                 </ul>
             </div>