audit: Tier 0 quick wins — EMAIL_REDIRECT_TO prod guard + storage routing + metadata masking

Tier 0.2: src/lib/env.ts now refuses boot when NODE_ENV=production AND
EMAIL_REDIRECT_TO is set. Sendmail logs the rewrite at warn (was debug)
so dev/staging windows where someone forgets to unset are immediately
visible.

Tier 0.6: backup_jobs.storage_path added to TABLES_WITH_STORAGE_KEYS in
src/lib/storage/migrate.ts. Flipping the storage backend used to
silently orphan every pg_dump artefact — last-resort recovery path is
now actually portable.

Tier 1.7: createAuditLog now runs metadata through maskSensitiveFields
(was only applied to old/new value diffs). Portal-auth, crm-invite,
hard-delete and email-accounts services were writing raw emails into
this column unbounded.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/env.ts

@@ -81,6 +81,21 @@ const envSchema = z.object({
     .enum(['true', 'false'])
     .default('false')
     .transform((v) => v === 'true'),
+}).superRefine((env, ctx) => {
+  // CRITICAL safety net: EMAIL_REDIRECT_TO is a dev/test feature that
+  // silently rewrites every outbound recipient. Leaving it set in prod
+  // funnels every customer email (invites, EOIs, portal magic links,
+  // contracts) to a single inbox. The audit caught this had only a
+  // `logger.debug` line as forensic trail. Refuse boot when both are
+  // simultaneously set in production.
+  if (env.NODE_ENV === 'production' && env.EMAIL_REDIRECT_TO) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      path: ['EMAIL_REDIRECT_TO'],
+      message:
+        'EMAIL_REDIRECT_TO must NOT be set in production — it silently rewrites every outbound email recipient. Unset it before deploying.',
+    });
+  }
 });
 
 export type Env = z.infer<typeof envSchema>;