chore(comments): re-point dangling supabase/migrations breadcrumbs

The Supabase purge deleted the archived supabase/migrations/.archived/
directory, but 12 src/ files still referenced its files by path in
JSDoc / TODO comments. The references were misleading (pointing to
deleted files), so re-point them at the canonical location of those
RPCs in db/migrations/0001_init.sql. No code or behavior changes.

Also fixed a stray 'supabase shim returns empty results' comment in
src/app/admin/page.tsx (the shim was already removed in Step 3 of
the refactor).

src/actions/tax.ts

@@ -152,12 +152,12 @@ async function getBrandTaxSettings(brandId: string): Promise<BrandTaxSettings |
 //
 // TODO(migration): the tax dashboard reads from the legacy `orders`
 // table via the `get_tax_summary` and `get_taxable_orders` SECURITY
-// DEFINER RPCs (supabase/migrations/095). Both the table and the RPCs
-// still exist; we call the RPCs through `pool.query` rather than the
-// Supabase REST gateway. When the SaaS rebuild's orders table grows a
-// `tax_amount` column or the tax dashboard is rebuilt against the new
-// schema, these helpers should be rewritten against the Drizzle
-// `orders` table directly.
+// DEFINER RPCs (originally from the now-archived supabase migrations;
+// consolidated into `db/migrations/0001_init.sql`). Both the table and
+// the RPCs still exist; we call the RPCs through `pool.query`. When the
+// SaaS rebuild's orders table grows a `tax_amount` column or the tax
+// dashboard is rebuilt against the new schema, these helpers should be
+// rewritten against the Drizzle `orders` table directly.
 
 export type TaxByStateRow = {
   state: string;