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/db/migrations/meta/_journal.json

@@ -64,6 +64,13 @@
       "when": 1790356758671,
       "tag": "0008_colossal_terrax",
       "breakpoints": true
+    },
+    {
+      "idx": 9,
+      "version": "6",
+      "when": 1790360862160,
+      "tag": "0009_amazing_cable",
+      "breakpoints": true
     }
   ]
 }