Add vendor publish to document system

Replace the old snapshot-based system for vendors with the publish
document system, mirroring the prior processing activity / DPIA / TIA
migration. Includes the GraphQL mutation, MCP tool, CLI command, n8n
operation, frontend publish dialog, e2e tests, and a prosemirror
register template covering vendor profile fields plus per-vendor
sections for services, contacts, risk assessments, compliance reports,
BAA and DPA agreements.

The vendor register lives as a generated DocumentTypeRegister document
on the organization, reused across publishes (the major version bumps
on every republish). Approvers can be passed in to create a draft
pending approval; otherwise the version is published immediately. The
frontend Vendors page exposes a Publish button and a Document link
button when the document exists, and pre-fills the previous default
approvers.

Remove snapshot mode entirely from vendors and their sub-entities: drop
snapshotId/sourceId from GraphQL Vendor type and VendorFilter; remove
SnapshotsTypeVendors from the snapshot registry and delete
Vendors.Snapshot, VendorSnapshotter interface and all
*.InsertVendorSnapshots methods on contacts, services, risk
assessments, compliance reports, BAA and DPA. Drop the snapshot routes
and banner from the frontend. The snapshot_id columns remain in the
database but are now filtered out with snapshot_id IS NULL.

Add Get/Upsert/Clear GeneratedDocumentID methods on Vendor backed by a
new vendors_document_id column on generated_documents, matching the
ProcessingActivity/Finding/Obligation pattern.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/docgen/generator.go

@@ -366,6 +366,73 @@ type (
 		LocalLawRisk           string
 		SupplementaryMeasures  string
 	}
+
+	VendorListData struct {
+		Title            string
+		OrganizationName string
+		CreatedAt        time.Time
+		TotalVendors     int
+		Rows             []VendorListRow
+	}
+
+	VendorListRow struct {
+		Name                          string
+		LegalName                     string
+		Description                   string
+		Category                      string
+		HeadquarterAddress            string
+		WebsiteURL                    string
+		PrivacyPolicyURL              string
+		ServiceLevelAgreementURL      string
+		DataProcessingAgreementURL    string
+		BusinessAssociateAgreementURL string
+		SubprocessorsListURL          string
+		StatusPageURL                 string
+		TermsOfServiceURL             string
+		SecurityPageURL               string
+		TrustPageURL                  string
+		Certifications                string
+		Countries                     string
+		BusinessOwner                 string
+		SecurityOwner                 string
+		Services                      []VendorListService
+		Contacts                      []VendorListContact
+		RiskAssessments               []VendorListRiskAssessment
+		ComplianceReports             []VendorListComplianceReport
+		BusinessAssociateAgreement    *VendorListAgreement
+		DataPrivacyAgreement          *VendorListAgreement
+	}
+
+	VendorListService struct {
+		Name        string
+		Description string
+	}
+
+	VendorListContact struct {
+		FullName string
+		Email    string
+		Phone    string
+		Role     string
+	}
+
+	VendorListRiskAssessment struct {
+		AssessedAt      string
+		ExpiresAt       string
+		DataSensitivity string
+		BusinessImpact  string
+		Notes           string
+	}
+
+	VendorListComplianceReport struct {
+		ReportName string
+		ReportDate string
+		ValidUntil string
+	}
+
+	VendorListAgreement struct {
+		ValidFrom  string
+		ValidUntil string
+	}
 )
 
 func BoolLabel(v bool) string {