chore: remediate pygienium audit findings

Dead code: 77 verified-unused exports, files (BackArrow, MenuBars,
cookies.ts, db/create.ts, schemas/comment.ts, security-headers.ts) and
12 unused dependencies removed
Comments: ~370 RESTATE comments stripped across 53 files; 2 verbose
blocks tightened; dead commented-out config removed
Complexity: bulkUpsert extracted into 11 per-entity helpers (CCN 156->~10);
login formHandler split into 3 submitters (CCN 63->~5); account page render
split into 8 section components (CCN 40); updatePost SQL builder rebuilt;
assert*Owned consolidated behind generic assertOwnedBy
Defensive guards: 4 redundant rethrow/nullish guards removed

src/components/Typewriter.tsx

@@ -138,9 +138,6 @@ export function Typewriter(props: {
         entries.forEach((entry) => {
           // If component leaves viewport while animating, we could pause
           // For now, we just ensure it starts when visible
-          if (!entry.isIntersecting && cleanupAnimation) {
-            // Component is off-screen - could add pause logic here if needed
-          }
         });
       },
       {