chore: prettier format all files, brotli, Sentry release tagging, CI gates

Prettier: auto-formatted 103 files to fix baseline. Prettier check in CI
  is now a hard gate (removed continue-on-error).

Brotli: installed libnginx-mod-http-brotli-filter/static. Enabled in nginx
  with brotli_static on for pre-compressed assets and comp_level 6.

Sentry releases: deploy script now exports VITE_APP_VERSION=<git-short-sha>
  before building so each Sentry release maps to an exact commit.
  CI also passes github.sha as VITE_APP_VERSION.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/pages/client/WelcomePage.tsx

@@ -15,7 +15,15 @@ export function WelcomePage() {
       >
         <PageHeroSection>
           <PageHero
-            icon={<img width="70" height="70" src={LotusLogo} alt="Lotus Chat" style={{ objectFit: "contain" }} />}
+            icon={
+              <img
+                width="70"
+                height="70"
+                src={LotusLogo}
+                alt="Lotus Chat"
+                style={{ objectFit: 'contain' }}
+              />
+            }
             title="Welcome to Lotus Chat"
             subTitle={
               <span>