Add migration to link Dutchie stores to dispensaries

Migration 029: Creates dispensary records for stores with dutchie_url
that don't have a dispensary_id yet, then links them.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/migrations/029_link_dutchie_stores_to_dispensaries.sql

@@ -0,0 +1,56 @@
+-- =====================================================
+-- Link Dutchie Stores to Dispensaries
+-- =====================================================
+-- Creates dispensary records for stores with dutchie_url that
+-- don't yet have a dispensary_id, then links them.
+
+-- Create dispensaries for unlinked stores with dutchie_url
+DO $$
+DECLARE
+    store_rec RECORD;
+    new_slug TEXT;
+    new_disp_id INTEGER;
+BEGIN
+    FOR store_rec IN
+        SELECT id, name, dutchie_url
+        FROM stores
+        WHERE dutchie_url IS NOT NULL AND dispensary_id IS NULL
+    LOOP
+        -- Extract slug from dutchie_url
+        new_slug := regexp_replace(
+            regexp_replace(store_rec.dutchie_url, '^https://dutchie\.com/(embedded-menu|dispensary)/', ''),
+            '/.*$', ''
+        );
+
+        -- Insert or update dispensary
+        INSERT INTO dispensaries (name, slug, address, city, state, provider_type, menu_url, created_at, updated_at)
+        VALUES (
+            store_rec.name,
+            new_slug,
+            'TBD',  -- Address to be filled in later
+            'TBD',  -- City to be filled in later
+            'AZ',   -- Default state
+            'dutchie',
+            store_rec.dutchie_url,
+            NOW(),
+            NOW()
+        )
+        ON CONFLICT (slug) DO UPDATE SET
+            provider_type = 'dutchie',
+            menu_url = EXCLUDED.menu_url,
+            updated_at = NOW()
+        RETURNING id INTO new_disp_id;
+
+        -- Link store to dispensary
+        UPDATE stores SET dispensary_id = new_disp_id WHERE id = store_rec.id;
+
+        RAISE NOTICE 'Linked store % (%) to dispensary %', store_rec.id, store_rec.name, new_disp_id;
+    END LOOP;
+END $$;
+
+-- Report on linked stores
+SELECT s.id as store_id, s.name as store_name, s.dispensary_id, d.slug as disp_slug
+FROM stores s
+JOIN dispensaries d ON d.id = s.dispensary_id
+WHERE s.dutchie_url IS NOT NULL
+ORDER BY s.id;