feat: complete launch & marketing layer

- Add marketing pages: blog, changelog, roadmap, waitlist, security, maintenance
- Add GDPR cookie consent banner with preference modal
- Add referral system with API routes for code generation/tracking
- Add waitlist API with referral support
- Add PWA support: manifest, service worker, install prompt
- Add onboarding flow with 6-step guided tour
- Add in-app notification center with bell dropdown
- Add admin launch checklist (32 items across 8 categories)
- Update landing page with trust badges
- Add Open Graph image and favicon
- Configure ESLint for PWA install patterns
- Add LAUNCH_CHECKLIST.md with go-to-market guide

Supabase migrations for:
- blog_posts and blog_categories tables
- waitlist_signups table
- roadmap_items table
- launch_checklist_items table

supabase/migrations/XXX_launch_checklist.sql

@@ -0,0 +1,22 @@
+-- Launch Checklist Progress Table
+-- Track user's launch preparation progress
+
+CREATE TABLE IF NOT EXISTS launch_checklist_progress (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id TEXT NOT NULL,
+    item_id TEXT NOT NULL,
+    completed BOOLEAN DEFAULT FALSE,
+    completed_at TIMESTAMPTZ,
+    notes TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE(user_id, item_id)
+);
+
+-- Indexes
+CREATE INDEX IF NOT EXISTS idx_checklist_user ON launch_checklist_progress(user_id);
+CREATE INDEX IF NOT EXISTS idx_checklist_completed ON launch_checklist_progress(completed) WHERE completed = TRUE;
+
+-- Grant permissions
+GRANT SELECT, INSERT, UPDATE ON launch_checklist_progress TO authenticated;
+GRANT ALL ON launch_checklist_progress TO service_role;