feat(admin-settings): radio field type + adopt for Documenso signing-order + send-mode

Adds a 'radio' SettingType the registry-driven admin form can render. Same
shape as 'select' (options list, enum validation, resolved/source badges),
but renders inline radio cards instead of a dropdown so each option's
consequences sit side-by-side for the admin.

Adopted on the two highest-stakes Documenso behaviour toggles:
- `eoi_send_mode` — Manual vs Auto signing-invitation dispatch
- `documenso_signing_order` — Parallel vs Sequential recipient flow

Both choices are binary and materially different (one auto-sends mail, the
other doesn't; one routes signing serially, the other in parallel), so the
upfront comparison beats a hidden dropdown.

`documenso_redirect_url` keeps its url-input — it's already a single
free-text field with no enum.

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

src/lib/settings/registry.ts

@@ -210,10 +210,10 @@ export const REGISTRY: SettingEntry[] = [
     label: 'Initial signing-invitation email behaviour',
     description:
       'Auto = the system sends the branded "please sign" email immediately when an EOI/contract/reservation is generated. Manual = the document is generated and the signing URL appears in the UI; a rep clicks "Send invitation" to dispatch. Applies to all document types, not just EOI.',
-    type: 'select',
+    type: 'radio',
     options: [
-      { value: 'manual', label: 'Manual (rep clicks Send after generation)' },
-      { value: 'auto', label: 'Auto (send branded email on generate)' },
+      { value: 'manual', label: 'Manual — rep clicks Send after generation' },
+      { value: 'auto', label: 'Auto — send branded email on generate' },
     ],
     scope: 'port',
     defaultValue: 'manual',
@@ -241,11 +241,11 @@ export const REGISTRY: SettingEntry[] = [
     section: 'documenso.behavior',
     label: 'Signing order',
     description:
-      'PARALLEL = all recipients can sign at once. SEQUENTIAL = each waits for the previous (v2 only - v1 always parallel).',
-    type: 'select',
+      'PARALLEL = all recipients can sign at once. SEQUENTIAL = each waits for the previous (v2 only — v1 always parallel).',
+    type: 'radio',
     options: [
-      { value: 'PARALLEL', label: 'Parallel - all recipients sign concurrently' },
-      { value: 'SEQUENTIAL', label: 'Sequential - order matters (v2 only)' },
+      { value: 'PARALLEL', label: 'Parallel — all recipients sign concurrently' },
+      { value: 'SEQUENTIAL', label: 'Sequential — order matters (v2 only)' },
     ],
     scope: 'port',
     defaultValue: 'PARALLEL',