Rename API test collection references: Bookmann → Bookhoard

Bruno API test updates:
- Update test assertions: X-Bookmann-* → X-Bookhoard-*
- Update variable names and references in test scripts
- Update documentation and comments in API tests

This is part 4 of the project rename to Bookhoard.

bruno/kobo/Kobo Initialization.bru

@@ -1,7 +1,7 @@
 meta {
-  name: Bookmann Kobo Sync
+  name: Bookhoard Kobo Sync
   type: collection
-  environment: Bookmann
+  environment: Bookhoard
 }
 
 ### Kobo Initialization Endpoint

bruno/kobo/Server Sync to Kobo.bru

@@ -37,8 +37,8 @@ Content-Type: application/json
 
 {
   "meta": {
-    "name": "Sync from Bookmann to Kobo",
-    "description": "Server-initiated sync pushing progress, bookmarks, and highlights from Bookmann to Kobo device",
-    "documentation": "Two-way sync endpoint. Allows Bookmann server to push updates to Kobo device, including reading progress, bookmarks, and highlights."
+    "name": "Sync from Bookhoard to Kobo",
+    "description": "Server-initiated sync pushing progress, bookmarks, and highlights from Bookhoard to Kobo device",
+    "documentation": "Two-way sync endpoint. Allows Bookhoard server to push updates to Kobo device, including reading progress, bookmarks, and highlights."
   }
 }

bruno/kobo/initialization.bru

@@ -17,5 +17,5 @@ assert {
   response.status == 200
   response.body.ContentId exists()
   response.body.Categories exists()
-  response.body.BookmannUUID exists()
+  response.body.BookhoardUUID exists()
 }