fix(web): handle empty-body 2xx responses; fix(store): sync DeleteDomainsNotInZones query with generated columns

req() in the frontend api client called res.json() on every non-204 2xx
response, which throws SyntaxError on the empty body returned by
POST .../customs (201) and similar endpoints. Read the response body once
as text and parse it only when non-empty, so any bodyless 2xx resolves
instead of rejecting. Added web/src/api/client.test.ts coverage that
exercises the real req() against a stubbed fetch for both the 201
(addCustom) and 204 (removeCustom) empty-body cases.

Also brought internal/store/queries/domains.sql's DeleteDomainsNotInZones
query back in sync with the hand-maintained internal/store/db/domains.sql.go
(RETURNING * -> explicit column list) since sqlc isn't installed in this
environment and the two files are kept aligned by hand.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018Yr8frsaxBgab1Aa7yfPuU

internal/store/queries/domains.sql

@@ -41,4 +41,4 @@ SELECT count(*) FROM domains WHERE last_check_status = 'drift';
 -- name: DeleteDomainsNotInZones :many
 DELETE FROM domains
 WHERE project_id = $1 AND provider_account_id = $2 AND zone_id <> ALL($3::text[])
-RETURNING *;
+RETURNING id, project_id, provider_account_id, zone_name, zone_id, template_id, created_at, last_check_status;