fix(pages.yml), feat(splash): unbreak GitHub Pages deploy, add live-sync card

Every splash deploy since 2026-07-08 has been failing silently: that
day's "pin pnpm version" commit added packageManager: pnpm@10.15.0 to
the root package.json (for Railway's Docker builds), which collided
with pages.yml's hardcoded pnpm/action-setup version: 9 — "Multiple
versions of pnpm specified." Six pushes in a row never actually
redeployed the splash; GitHub Pages was quietly serving a stale build
this whole time. Dropped the hardcoded version so action-setup reads
packageManager from package.json instead, matching what Railway's
Dockerfiles already assume.

While rebuilding locally to verify the fix, pnpm resynced
splash/pnpm-lock.yaml to what splash/package.json already declared
(astro ^7.0.5, astro-pagefind ^2.0.0) — the committed lockfile had
drifted to older astro 6.3.1 / astro-pagefind 1.8.6 resolutions.

Also added a feature-highlight card ("Build the corpus together,
live") covering the one shipped capability with no card yet: NATS
broadcast sync across signed-in sessions on the same workspace. The
other five build-cycle additions (SurrealDB canonical layer, didi.sh
identity) already had marketing coverage via the existing
curate-sources-by-strategy and one-source-of-truth cards.

Files changed:
- .github/workflows/pages.yml
- splash/pnpm-lock.yaml
- splash/src/content/feature-highlights/live-together.md (new)

Author: mpstaton

.github/workflows/pages.yml

@@ -35,8 +35,6 @@ jobs:
 
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
-        with:
-          version: 9
 
       - name: Setup Node
         uses: actions/setup-node@v4