Refactor to generic ERP base

Remove influencer-specific features (campaigns, TikTok, gifts, shadow ledger,
contracts, briefings) and consolidate into a clean ERP foundation with core
bookkeeping, invoicing, receipts, tax reporting, and calendar functionality.
Reorganize database migrations into a clean numbered sequence.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/api/push/subscribe/route.ts

@@ -81,7 +81,6 @@ export async function POST(request: Request) {
         user_id: user.id,
         tax_deadlines_enabled: true,
         invoice_reminders_enabled: true,
-        campaign_deadlines_enabled: true,
         push_enabled: true,
         email_enabled: true,
         quiet_start: '21:00',