fix(gateway): drop vitest.config.ts from tsconfig include

The bootstrap hotfix PR #440 added `vitest.config.ts` to
apps/gateway/tsconfig.json's include list, which broke `pnpm build`
because the file sits outside `rootDir: src` and tsc emits TS6059
for anything in the program that isn't under rootDir.

The publish pipeline runs `pnpm build` (via turbo) and failed on
main post-merge, blocking the mosaic-v0.0.26 release. The CI
workflow passed because it only runs typecheck/lint/format/test
(typecheck uses tsconfig.typecheck.json with rootDir=../..).

Vitest doesn't need its config file in any tsconfig's program —
it loads the file directly via Node ESM. Reverting the include
line restores the build without affecting the new e2e test, which
lives at src/admin/bootstrap.e2e.spec.ts and is already picked up
by the src/**/* glob.

Verified locally: build ✓ typecheck ✓ 351 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/gateway/tsconfig.json

@@ -8,6 +8,6 @@
     "module": "NodeNext",
     "moduleResolution": "NodeNext"
   },
-  "include": ["src/**/*", "vitest.config.ts"],
+  "include": ["src/**/*"],
   "exclude": ["node_modules", "dist"]
 }