docs: add example.env and document all environment variables

- Create example.env with all 31 environment variables documented
- Update docker-compose.yml to use env_file directive
- Update doc/deployment.md with Quick Start and missing variables
- Add OXICLOUD_BASE_URL and WOPI configuration docs
- Update README.md Docker section with .env setup
- Remove duplicate port mapping (incorporates 4577e56)
- Fix server port default from 8085 to 8086

src/application/services/share_service.rs

@@ -772,6 +772,6 @@ mod tests {
         assert_eq!(share_dto.item_id, "test_file_id");
         assert_eq!(share_dto.item_type, "file");
         assert!(share_dto.has_password);
-        assert!(share_dto.url.starts_with("http://127.0.0.1:8085/s/"));
+        assert!(share_dto.url.starts_with("http://127.0.0.1:8086/s/"));
     }
 }