Add typescript to root devDependencies

Workspace packages run `tsc` in their typecheck scripts but don't declare
typescript as a dep — they relied on it being hoisted. On a clean local
install the binary wasn't present at node_modules/.bin/tsc, so every
package failed with `tsc: command not found`. Declaring typescript at the
root makes the dependency explicit and removes the latent fragility.

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

pnpm-lock.yaml

@@ -182,6 +182,9 @@ importers:
       turbo:
         specifier: ^2.9.8
         version: 2.9.8
+      typescript:
+        specifier: 'catalog:'
+        version: 5.9.3
       typescript-eslint:
         specifier: ^8.59.1
         version: 8.59.1(eslint@10.3.0(jiti@2.6.1))(typescript@5.9.3)