Rename project documentation: Bookmann → Bookhoard

Documentation updates:
- Update README.md title and all references
- Update PROJECT_GUIDELINES.md title and guidelines
- Update all documentation files in docs/ directory
- Update device setup guides (Kobo, KOReader)
- Update API and architecture documentation
- Update completion summaries and progress reports

This is part 5 of the project rename to Bookhoard.

docs/COLLECTIONS_API.md

@@ -378,9 +378,9 @@ Collections allow you to organize your books into custom categories with:
 ```
 
 **Sync Directions**:
-- `bidirectional`: Sync both ways between Bookmann and device
-- `book_to_device`: Bookmann → Device only
-- `device_to_book`: Device → Bookmann only
+- `bidirectional`: Sync both ways between Bookhoard and device
+- `book_to_hoard`: Bookhoard → Device only
+- `device_to_hoard`: Device → Bookhoard only
 - `none`: No sync (mapping only)
 
 **Response** (201 Created): Mapping object
@@ -399,7 +399,7 @@ Collections allow you to organize your books into custom categories with:
 ```json
 {
   "device_shelf_name": "Science Fiction",
-  "sync_direction": "book_to_device"
+  "sync_direction": "book_to_hoard"
 }
 ```