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/env/client.ts

@@ -38,16 +38,7 @@ export const validateClientEnv = (
   return envVars as unknown as ClientEnv;
 };
 
-const validateAndExportEnv = (): ClientEnv => {
-  try {
-    const validated = validateClientEnv(import.meta.env);
-    return validated;
-  } catch (error) {
-    throw error;
-  }
-};
-
-export const env = validateAndExportEnv();
+export const env = validateClientEnv(import.meta.env);
 
 export const isMissingEnvVar = (varName: string): boolean => {
   return !import.meta.env[varName] || import.meta.env[varName]?.trim() === "";