feat(documents): create-document wizard MVP + service dispatch

Implements createFromWizard and createFromUpload service paths covering
the documenso-template, in-app, and upload pathways. Persists subject
FK, signers, watchers, and the per-document reminder controls
(remindersDisabled / reminderCadenceOverride) introduced in PR1. New
POST /api/v1/documents/wizard route and a functional /documents/new UI
with type/source/template/signers/reminders sections. Drag-handle
reorder, watcher autocomplete picker, and PDF preview defer to the
PR10 polish sweep.

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

src/lib/validators/documents.ts

@@ -17,6 +17,58 @@ export const updateDocumentSchema = z.object({
   status: z.enum(DOCUMENT_STATUSES).optional(),
 });
 
+const wizardSignerSchema = z.object({
+  signerName: z.string().min(1),
+  signerEmail: z.string().email(),
+  signerRole: z.enum(['client', 'sales', 'approver', 'developer', 'other']),
+  signingOrder: z.number().int().min(1),
+});
+
+export const createDocumentWizardSchema = z
+  .object({
+    source: z.enum(['template', 'upload']).default('template'),
+    templateId: z.string().optional(),
+    uploadedFileId: z.string().optional(),
+
+    documentType: z.enum(DOCUMENT_TYPES),
+    title: z.string().min(1).max(200),
+    notes: z.string().optional(),
+
+    interestId: z.string().optional(),
+    reservationId: z.string().optional(),
+    clientId: z.string().optional(),
+    companyId: z.string().optional(),
+    yachtId: z.string().optional(),
+
+    signers: z.array(wizardSignerSchema).optional(),
+    signingMode: z.enum(['sequential', 'parallel']).default('sequential'),
+    pathway: z.enum(['documenso-template', 'inapp', 'upload']).default('documenso-template'),
+
+    watchers: z.array(z.string()).default([]),
+
+    reminderCadenceOverride: z.number().int().min(1).max(365).nullable().optional(),
+    remindersDisabled: z.boolean().default(false),
+
+    autoPlaceFields: z.boolean().default(true),
+    sendImmediately: z.boolean().default(true),
+  })
+  .refine(
+    (d) =>
+      [d.interestId, d.reservationId, d.clientId, d.companyId, d.yachtId].filter(Boolean).length ===
+      1,
+    { message: 'Exactly one subject (interest/reservation/client/company/yacht) is required' },
+  )
+  .refine((d) => d.source !== 'template' || Boolean(d.templateId), {
+    path: ['templateId'],
+    message: 'templateId is required when source=template',
+  })
+  .refine((d) => d.source !== 'upload' || Boolean(d.uploadedFileId), {
+    path: ['uploadedFileId'],
+    message: 'uploadedFileId is required when source=upload',
+  });
+
+export type CreateDocumentWizardInput = z.infer<typeof createDocumentWizardSchema>;
+
 export const documentsHubTabs = [
   'all',
   'awaiting_them',