Fix ambiguous-column bug in merchant-profile resolution

get_merchant_profile_for_product selected the bare MERCHANT_PROFILE_COLS list
while JOINing products (which also has an id), so SQLite raised "ambiguous
column name: id" on every execution. The function runs on every purchase, so
every paid purchase on 0.2.0:52 returned HTTP 500. Replace the JOIN with an
equivalent correlated subquery, keeping merchant_profiles the only table in
FROM; behavior on NULL/missing merchant_profile_id is unchanged (no row, caller
falls back to the default profile).

Also from the verification pass:
- Add merchant_profile_provider_resolution_queries_round_trip, exercising the
  previously untested runtime-prepared resolution / CRUD / preference queries.
- Repair three test call sites for the new create_invoice / create_subscription
  params; capture the response body in the paid_purchase status assertion.
- Align manifest license to LicenseRef-Keysat-1.0; drop an unused import.

startos/manifest/index.ts

@@ -14,7 +14,7 @@ import { short, long } from './i18n'
 export const manifest = setupManifest({
   id: 'keysat',
   title: 'Keysat Licensing',
-  license: 'LicenseRef-Proprietary',
+  license: 'LicenseRef-Keysat-1.0',
   packageRepo: 'https://github.com/keysat-xyz/keysat-startos',
   upstreamRepo: 'https://github.com/keysat-xyz/keysat',
   marketingUrl: 'https://keysat.xyz',