pnpm check: use tsc -b so it catches what pnpm build catches

`tsc --noEmit` and `tsc -b` apply slightly different narrowing rules
on project-reference codebases — the prior check missed the spawn_pane
hostId narrowing bug (commit e1ceaab) that pnpm build immediately
flagged. Both tsconfig.app.json and tsconfig.node.json already set
`noEmit: true`, so `tsc -b` does no emission — the only difference
is build-mode dependency tracking + slightly stricter type checks.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -9,7 +9,7 @@
     "preview": "vite preview",
     "test": "vitest run",
     "test:watch": "vitest",
-    "check": "tsc --noEmit",
+    "check": "tsc -b",
     "build:mcpb": "node scripts/build-mcpb.mjs",
     "gen:readme": "node scripts/gen-readme-shortcuts.mjs",
     "tauri": "tauri"