feat: Sprint 1 - Deep discovery, lead persistence, and dashboard nav

- Add BacklinkOutreachScraper (Exa + DuckDuckGo deep scraping)
- Extend DB and Pydantic models for lead enrichment columns
- Add StorageService methods for lead CRUD with auto-migration
- Add backend endpoints: deep discover, campaign detail, lead management
- Extend frontend API client and store with discovery + lead actions
- Create BacklinkOutreachDashboard component with campaigns/discover/leads tabs
- Register route at /backlink-outreach under SEO feature flag
- Add nav entry under Enterprise & Advanced in tool categories

frontend/src/data/toolCategories.ts

@@ -18,7 +18,8 @@ import {
   CalendarMonth as CalendarIcon,
   AudioFile as AudioIcon,
   Image as ImageIcon,
-  VideoLibrary as VideoIcon
+  VideoLibrary as VideoIcon,
+  Link as LinkIcon
 } from '@mui/icons-material';
 import MenuBookIcon from '@mui/icons-material/MenuBook';
 import { ToolCategories } from '../components/shared/types';
@@ -127,6 +128,16 @@ export const toolCategories: ToolCategories = {
             isPinned: true,
             isHighlighted: true
           },
+          {
+            name: 'Backlink Outreach',
+            description: 'Discover guest post opportunities with AI-powered deep scraping',
+            icon: React.createElement(LinkIcon),
+            status: 'beta',
+            path: '/backlink-outreach',
+            features: ['AI Discovery', 'Guest Post Opportunities', 'Campaign Management'],
+            isPinned: true,
+            isHighlighted: true
+          },
           {
             name: 'AI Content Strategy Generator',
             description: 'Comprehensive content planning with market intelligence',