refactor(scripts): fold check:fixtures into check:type

A single top-level `vp run check:type` should fan out (-r) and fully type-check
every package, fixtures included — no separate top-level check:fixtures step.
runtime-tests' check:type now runs its main tsc then its fixtures tsc
(check:fixtures stays as a runnable sub-script). Drop the root check:fixtures
entry and its standalone step in ready.

packages/runtime-tests/package.json

@@ -7,7 +7,7 @@
     "test": "vp run test:integration && vp run test:pty",
     "test:integration": "vp test",
     "test:pty": "vp test run --config vitest.pty.config.ts --passWithNoTests",
-    "check:type": "tsc --noEmit",
+    "check:type": "tsc --noEmit && vp run check:fixtures",
     "check:fixtures": "tsc -p integration/pty/fixtures/tsconfig.json --noEmit"
   },
   "devDependencies": {