bug: seed_category_mappings.sql references categories not in initial schema — npx supabase db reset fails

[cje-bridgyr]

Symptom

npx supabase db reset fails partway through with an FK violation while applying supabase/migrations/20260304021726_seed_category_mappings.sql. The local Supabase stack cannot be brought up cleanly until this is fixed.

Root cause

20260304021726_seed_category_mappings.sql inserts rows into public.category_mappings whose category_id values reference categories that do not exist in the seed data of 00000000000000_initial_schema.sql.

The only seeded category IDs in the initial schema are:

• salary-income
• internal-transfer
• external-transfer
• round-up
• interest
• investments

The seed-mappings migration tries to insert rows referencing categories like `groceries`, etc., which were never inserted. The FK constraint `category_mappings_category_id_fkey` fails on the first such row, aborting the migration and leaving the local DB in a partial state.

Impact

• `npx supabase db reset` is broken for any contributor cloning fresh.
• New schema work cannot be verified against the real local stack — has to use a throwaway Postgres container with auth stubs.
• Blocks UI development for any feature that needs a working local Supabase.

Possible fixes

1. Add the missing category rows to `00000000000000_initial_schema.sql` (preferred — keeps initial schema self-consistent).
2. Wrap the mappings inserts in `INSERT ... ON CONFLICT DO NOTHING` and pre-insert the categories at the top of `20260304021726_seed_category_mappings.sql` itself.
3. Drop the seed-mappings migration if the data isn't load-bearing for current features.

Reproduction

```bash
git clone https://github.com/BenLaurenson/PiggyBack.git
cd PiggyBack
npm install
npx supabase start
npx supabase db reset

fails on 20260304021726_seed_category_mappings.sql

```

Discovered during

Wise Business Accounting Phase 1A foundation implementation (May 2026). Forced the implementation to verify schema changes against a `postgres:15` Docker container with hand-rolled `auth.uid()`, `authenticated`, and `service_role` stubs rather than the real Supabase stack.