fix(audit-tier-2-routes): manual NextResponse.json error sweep + admin form banners

Two final waves of error-surface hygiene closing the audit's MED §12 +
HIGH §15 + HIGH §17 findings:

* 50 route files swept (61 sites): manual NextResponse.json({error,
  status: 4xx|5xx}) early-returns replaced by typed throws +
  errorResponse(err) at the catch.
  - Super-admin gates (13 sites) use new requireSuperAdmin(ctx, action)
    helper from src/lib/api/helpers.ts so denials hit the audit log.
  - Path-param + body validation 400s become ValidationError throws.
  - 404s become NotFoundError or CodedError('NOT_FOUND') for AI
    feature-flag paths.
  - 11 manual 5xx returns now re-throw so error_events captures the
    request-id (the admin error inspector becomes usable from real
    incidents).
  - website-analytics 200-with-error anti-pattern flipped to 409 +
    UMAMI_NOT_CONFIGURED. 502 upstream paths use UMAMI_UPSTREAM_ERROR.
  - 11 sites intentionally preserved: storage/[token] anti-enumeration
    token-failure paths, webhook-secret 401, "Unknown port" 400 in
    public intake.

* 7 admin forms (roles, users, ports, webhooks, custom-fields,
  document-templates, tags) gain a formatErrorBanner() helper from
  src/lib/api/toast-error.ts that builds a multi-line "Error code / Reference ID"
  banner — the rep can copy the request id when reporting a failed
  save.  Banners get whitespace-pre-line so newlines render.

Test status: 1168/1168 vitest, tsc clean.

Refs: docs/audit-comprehensive-2026-05-05.md MED §12 (auditor-F Issue 1)
+ HIGH §15 (auditor-F Issue 2) + HIGH §17 (auditor-H Issue 2).

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

src/components/admin/roles/role-form.tsx

@@ -1,4 +1,5 @@
 'use client';
+import { formatErrorBanner } from '@/lib/api/toast-error';
 
 import { useState, useEffect } from 'react';
 import { Button } from '@/components/ui/button';
@@ -202,7 +203,7 @@ export function RoleForm({ open, onOpenChange, role, onSuccess }: RoleFormProps)
       onSuccess();
       onOpenChange(false);
     } catch (err: unknown) {
-      const message = err instanceof Error ? err.message : 'Something went wrong';
+      const message = formatErrorBanner(err);
       setError(message);
     } finally {
       setLoading(false);
@@ -283,7 +284,7 @@ export function RoleForm({ open, onOpenChange, role, onSuccess }: RoleFormProps)
             </Accordion>
           </ScrollArea>
 
-          {error && <p className="mt-2 text-sm text-destructive">{error}</p>}
+          {error && <p className="mt-2 whitespace-pre-line text-sm text-destructive">{error}</p>}
 
           <SheetFooter className="mt-4">
             <Button