feat(documenso): full v2 endpoint coverage + sequential signing + redirectUrl

Wire up the remaining version-aware paths so a port pointed at Documenso 2.x
takes the v2 endpoint on every CRUD operation, with two new v2-only settings
exposed in admin UI.

documenso-client.ts:
- createDocument: v2 multipart /envelope/create + getDocument follow-up to
  return the full doc shape (v1 path unchanged)
- sendDocument: v2 /envelope/distribute (returns per-recipient signingUrl in
  the same response — eliminates the v1 separate-GET round-trip)
- sendReminder: v2 /envelope/redistribute with recipientIds filter
- downloadSignedPdf: v2 /envelope/{id}/download
- CreateDocumentMeta type: { subject, message, redirectUrl, signingOrder }
  threaded through v1 + v2 paths (v1 ignores signingOrder)

port-config.ts:
- New settings: documenso_signing_order (PARALLEL/SEQUENTIAL, v2-only),
  documenso_redirect_url (both versions honour)
- PortDocumensoConfig gains signingOrder + redirectUrl

documenso-payload.ts:
- DocumensoTemplatePayload.meta gains signingOrder
- buildDocumensoPayload reads from options.signingOrder, omits when null

document-templates.ts (EOI template flow):
- Pass docCfg.signingOrder + docCfg.redirectUrl into buildDocumensoPayload

documents.service.ts (sendForSigning uploaded-doc flow):
- Pass portId to documensoCreate + documensoSend (was missing)
- Thread signingOrder + redirectUrl via the new meta param

Admin Documenso settings page:
- v2 benefits card updated: now lists envelope CRUD, one-call send,
  sequential enforcement, post-sign redirect as wired (was roadmap)
- Roadmap callout pruned to the three remaining deferred items:
  template/use migration, /envelope/update, non-SIGNER recipient roles
- New "v2 signing behaviour" SettingsFormCard with the two new settings

Template flow stays on /api/v1/templates/{id}/generate-document by design —
Documenso 2.x accepts v1 endpoints via backward compat; full migration to
v2 /template/use requires per-template field-ID capture (admin schema work,
deferred).

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

src/lib/services/document-templates.ts

@@ -902,7 +902,11 @@ async function generateAndSignViaDocumensoTemplate(
     developerEmail: signers.developer.email,
     approverName: signers.approver.name,
     approverEmail: signers.approver.email,
-    redirectUrl: env.APP_URL,
+    // Prefer per-port post-signing redirect (typically marketing-site
+    // /sign/success on v2). Falls back to APP_URL on v1 / when unset.
+    redirectUrl: docCfg.redirectUrl ?? env.APP_URL,
+    // v2-only signing-order enforcement. v1 instances ignore this key.
+    ...(docCfg.signingOrder ? { signingOrder: docCfg.signingOrder } : {}),
   });
 
   const documensoDoc = await documensoGenerateFromTemplate(