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/server/controllers/project.controller.ts

@@ -4,6 +4,10 @@ import {
   updateProjectSettingsSchema,
 } from "../../shared/validation/project-structure.schemas.js";
 import { createProjectSettingsUpdateProjectCommand } from "../../domain/models/project-settings-project-command.model.js";
+import {
+  projectCoverFields,
+  type ProjectCoverField,
+} from "../../shared/constants/project-cover.js";
 import { projectCommandService } from "../composition/project-command-stores.js";
 import { projectRepository } from "../composition/application-repositories.js";
 import { respondWithProjectCommandError } from "./project-command.controller.js";
@@ -46,12 +50,27 @@ export async function updateProjectSettings(req: Request, res: Response) {
   }
 
   const { expectedRevision, ...settings } = parsed.data;
+  const current = await projectRepository.findById(projectId);
+  if (!current) {
+    return res.status(404).json({ error: "Project not found" });
+  }
+  // Cover fields are optional in the request and keep their current value
+  // when omitted. `expectedRevision` rejects a project changed meanwhile.
+  const coverValues = Object.fromEntries(
+    projectCoverFields.map((field) => [
+      field,
+      settings[field] === undefined ? current[field] : settings[field],
+    ])
+  ) as Record<ProjectCoverField, string | null>;
   try {
     const result = projectCommandService.executeUser({
       projectId,
       expectedRevision,
       description: "Projekteinstellungen bearbeiten",
-      command: createProjectSettingsUpdateProjectCommand(settings),
+      command: createProjectSettingsUpdateProjectCommand({
+        ...settings,
+        ...coverValues,
+      }),
     });
     const project = await projectRepository.findById(projectId);
     if (!project) {