Add print cover fields and office profile

- Project settings gain siteAddress, workStage, projectLead and
  projectEditor (project.update-settings schema version 3, migration 0009);
  versions 2 and 1 stay executable and keep the current cover values.
  Snapshot schema 6 carries the fields; older versions upgrade with null.
- Global office profile (office name/address) next to the document logo:
  table document_branding_settings, PUT /api/document-branding/office,
  editable from the print view toolbar.
- Cover page reads all fields; empty values show the "[ergänzen]" marker.
  The Planstände editor column shows the project editor.
- Shared logo constants moved to a dependency-free module so the Next.js
  bundler can import them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/shared/validation/project-structure.schemas.ts

@@ -4,8 +4,22 @@ import {
   distributionBoardSupplyTypes,
   type DistributionBoardInfoField,
 } from "../constants/distribution-board.js";
+import {
+  projectCoverFieldMaxLengths,
+  type ProjectCoverField,
+} from "../constants/project-cover.js";
 import { expectedProjectRevisionSchema } from "./project-command.schemas.js";
 
+// Empty text is stored as null so "not entered" has one representation.
+const optionalCoverValueSchema = (field: ProjectCoverField) =>
+  z
+    .string()
+    .trim()
+    .max(projectCoverFieldMaxLengths[field])
+    .nullable()
+    .transform((value) => (value ? value : null))
+    .optional();
+
 export const createProjectSchema = z.object({
   name: z.string().trim().min(1).max(200),
   internalProjectNumber: z.string().trim().max(100).optional(),
@@ -34,6 +48,11 @@ export const updateProjectSettingsSchema = z
       .refine((values) => new Set(values).size === values.length, {
         message: "Netzarten dürfen nicht mehrfach ausgewählt werden.",
       }),
+    // Print cover fields; omitted fields keep their current value.
+    siteAddress: optionalCoverValueSchema("siteAddress"),
+    workStage: optionalCoverValueSchema("workStage"),
+    projectLead: optionalCoverValueSchema("projectLead"),
+    projectEditor: optionalCoverValueSchema("projectEditor"),
   })
   .strict();