Adds email approval & Postmark integration for negotiations

Enables users to approve and send negotiation emails directly via Postmark after configuring a server token in settings. Introduces new debt statuses ("approved", "sent"), UI for token management, and approval/rejection flows. Refactors notifications to use a modern toast library, adjusts dashboard status filters, and updates DB schema for new flows.

Empowers compliant, user-controlled negotiation and automated email delivery.

supabase/migrations/20250607009000_add_postmark_server_token.sql

@@ -0,0 +1,14 @@
+/*
+  # Add Postmark Server Token
+
+  1. Changes
+    - Add postmark_server_token column to user_profiles table
+    - This will be used for sending approved emails
+*/
+
+-- Add postmark_server_token to user_profiles
+ALTER TABLE user_profiles 
+ADD COLUMN IF NOT EXISTS postmark_server_token text;
+
+-- Add comment for documentation
+COMMENT ON COLUMN user_profiles.postmark_server_token IS 'Postmark server token for sending approved negotiation emails';

supabase/migrations/20250607010000_add_postmark_and_sent_status.sql

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+-- Add postmark_server_token to user_profiles table
+ALTER TABLE user_profiles 
+ADD COLUMN IF NOT EXISTS postmark_server_token TEXT;
+
+-- Update debts table status constraint to include 'sent'
+ALTER TABLE debts 
+DROP CONSTRAINT IF EXISTS debts_status_check;
+
+ALTER TABLE debts 
+ADD CONSTRAINT debts_status_check 
+CHECK (status IN ('received', 'negotiating', 'sent', 'settled', 'failed', 'opted_out'));
+
+-- Create index on postmark_server_token for faster lookups
+CREATE INDEX IF NOT EXISTS idx_user_profiles_postmark_token 
+ON user_profiles(user_id) WHERE postmark_server_token IS NOT NULL;
+
+-- Add comment for documentation
+COMMENT ON COLUMN user_profiles.postmark_server_token IS 'Postmark server token for sending negotiation emails';

supabase/migrations/20250607011000_add_approved_status.sql

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+-- Add 'approved' status to debts table
+ALTER TABLE debts 
+DROP CONSTRAINT IF EXISTS debts_status_check;
+
+ALTER TABLE debts 
+ADD CONSTRAINT debts_status_check 
+CHECK (status IN ('received', 'negotiating', 'approved', 'sent', 'settled', 'failed', 'opted_out'));