fix(webui): template save maps the new template-exists refusal to 409, not outcome-unknown (#1873)

f6c added template-exists for a save under a taken name. The template
route had no entry for it, so a duplicate save answered 503
outcome-unknown. Map it to 409 and move the SP8 pin.

packages/webui/src/template-http.mjs

@@ -28,7 +28,7 @@ const LIMIT = 4096;
 const codes = {
   'invalid-request': 400, 'template-secret-suspected': 400, 'starter-pack-invalid': 400,
   'project-not-found': 404,
-  'pack-plan-stale': 409, 'starter-pack-template-changed': 409, 'organization-busy': 409,
+  'pack-plan-stale': 409, 'starter-pack-template-changed': 409, 'organization-busy': 409, 'template-exists': 409,
   'human-required': 403, 'read-only': 403,
   'not-configured': 503, 'no-bus-host': 503,
 };

packages/webui/tests/template-http.test.mjs

@@ -85,7 +85,7 @@ test('SP8 the owner previews a template (nothing written), saves it with the dig
   assert.equal(readFileSync(f.saved('demo-shape'), 'utf8'), preview.json);
   assert.deepEqual(readFileSync(f.file), before, 'the organization file is unchanged');
   const [again, againBody] = await call(f, `${ORG}/templates`, 'POST', { name: 'demo-shape', digest: preview.digest });
-  assert.deepEqual([again, againBody.error], [400, 'invalid-request']);
+  assert.deepEqual([again, againBody.error], [409, 'template-exists']);
   const [, list] = await call(f, `${ORG}/templates`);
   assert.deepEqual(list.templates.map(x => [x.name, x.scope]), [['demo-shape', 'org']]);
   // The preview and the list went over the read; only the saves used the fenced writer.