Add Lead Scoring ML + Email Sequences/Drip Campaigns

Lead Scoring:
- lead_scoring_config table with configurable feature weights
- Scoring engine: boolean, keyword, and range-based feature scoring
- Settings tab: configure scoring features, run scoring on all leads
- ml_score + ml_score_details columns on leads table
- API: /api/leads/score, /api/leads/score/config
- mlScore returned in lead detail and list APIs

Email Campaigns:
- email_campaigns, email_campaign_steps, subscribers, logs tables
- Campaign list page with status badges and subscriber counts
- Campaign detail with step management, subscriber search/add, send
- Drip logic: steps with configurable delay days, template variables
- Variable replacement ({{name}}, {{email}}) in email bodies
- Sidebar: Campaigns nav item

src/app/(dashboard)/settings/page.tsx

@@ -7,7 +7,8 @@ import { UserPreferencesForm } from "@/components/settings/user-preferences-form
 import { ThemeSettings } from "@/components/settings/theme-settings"
 import { NotificationSettings } from "@/components/settings/notification-settings"
 import { CustomFieldsManager } from "@/components/settings/custom-fields-manager"
-import { Building2, User, Palette, Bell, ListChecks } from "lucide-react"
+import { LeadScoringSettings } from "@/components/settings/lead-scoring-settings"
+import { Building2, User, Palette, Bell, ListChecks, Gauge } from "lucide-react"
 
 export default function SettingsPage() {
   const tabs = [
@@ -16,6 +17,7 @@ export default function SettingsPage() {
     { value: "theme", label: "Theme", icon: Palette, component: ThemeSettings },
     { value: "notifications", label: "Notifications", icon: Bell, component: NotificationSettings },
     { value: "custom-fields", label: "Custom Fields", icon: ListChecks, component: CustomFieldsManager },
+    { value: "lead-scoring", label: "Lead Scoring", icon: Gauge, component: LeadScoringSettings },
   ]
 
   return (