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>

e2e/mcp/snapshot_test.go

@@ -29,8 +29,8 @@ func TestMCP_Snapshot(t *testing.T) {
 	mc := testutil.NewMCPClient(t, owner)
 	orgID := owner.GetOrganizationID().String()
 
-	// Create a vendor so the snapshot has data
-	factory.CreateVendor(owner)
+	// Create a risk so the snapshot has data
+	factory.CreateRisk(owner)
 
 	// Take snapshot
 	var takeResult struct {
@@ -41,7 +41,7 @@ func TestMCP_Snapshot(t *testing.T) {
 	mc.CallToolInto("takeSnapshot", map[string]any{
 		"organizationId": orgID,
 		"name":           factory.SafeName("Snapshot"),
-		"snapshotsType":  "VENDORS",
+		"snapshotsType":  "RISKS",
 	}, &takeResult)
 	require.NotEmpty(t, takeResult.Snapshot.ID)