App versioning + the create page's missing top padding

Versioning: package.json carries the app version (0.1.2 here; one bump per
task with `npm run version:bump`, patch 0-9 rolling into the minor at 10),
baked into the build via lib/version.ts, reported by /api/healthz and shown
in Settings next to the running commit. AGENTS.md documents the rule; the
native suite checks both the API and the Settings row.

Fix: on desktop the app header is hidden, so every page owns its top padding —
/create was the only one without `lg:pt-10`, which slammed the Study deck /
Make my homework switch against the top of the window while /homework had a
comfortable gap. Both now sit at 40px; the wizard suite asserts the clearance
and that the two pages stay in step (90 checks).

SW -> freezmo-v50.

app/api/healthz/route.ts

@@ -1,6 +1,8 @@
 import { readFileSync } from "node:fs";
 import path from "node:path";
 
+import { APP_VERSION } from "@/lib/version";
+
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
 
@@ -25,6 +27,7 @@ export async function GET() {
   return Response.json(
     {
       ok: true,
+      version: APP_VERSION,
       commit,
       short: release?.short ?? commit.slice(0, 7),
       builtAt: release?.builtAt ?? null,