ci: drop the redundant standalone tsc step

Caught by the first real CI run: a bare `pnpm exec tsc --noEmit` fails
on a clean checkout because Next's own ambient types (LayoutProps and
friends, from .next/types) don't exist until a build has run at least
once. Locally this never surfaced since .next was always already
present from earlier dev/build runs. `next build` performs an
equivalent (and more complete) type check as part of its own process,
so the separate step was both redundant and the thing that broke.

.gitea/workflows/ci.yml

@@ -26,9 +26,10 @@ jobs:
       - name: Lint
         run: pnpm lint
 
-      - name: Type check
-        run: pnpm exec tsc --noEmit
-
+      # `next build` runs its own full TypeScript check as part of the
+      # build - a separate `tsc --noEmit` here would fail on a clean
+      # checkout anyway, since it needs .next/types (generated by this
+      # same build) for Next's own ambient types like LayoutProps.
       - name: Build
         run: pnpm build