feat(golemcore/notion): add database and file operations

[golemcore1]

Summary

• add database-oriented Notion operations for databases, data sources, and database entries
• add file upload and page attachment operations for Notion file workflows
• extend notion_vault tests to cover the new operations and service behavior

What changed

Databases and data sources

• added create_database, read_database, and update_database
• added create_data_source, read_data_source, and update_data_source
• added query_database with support for either database_id or explicit data_source_id
• added create_database_entry, read_database_entry, and update_database_entry

Files

• added list_page_files
• added create_file_upload, upload_file_content, complete_file_upload, read_file_upload, and list_file_uploads
• added attach_file_to_page for file/image/pdf/audio/video blocks

Implementation details

• expanded NotionApiClient to support database, data source, page property, and file upload endpoints
• added summary DTOs for databases, data sources, page details, file uploads, child items, and file attachments
• updated NotionVaultService and NotionVaultToolProvider schemas/dispatching to expose the new capabilities
• kept existing page-note behavior intact while enriching list_directory and read_note responses with more file metadata

Validation

• ../apache-maven-3.9.11/bin/mvn -B -ntp -pl golemcore/notion -am -DskipTests compile
• ../apache-maven-3.9.11/bin/mvn -B -ntp -pl golemcore/notion -am -Dtest=NotionVaultToolProviderTest,NotionVaultServiceTest -Dsurefire.failIfNoSpecifiedTests=false -DforkCount=0 -DreuseForks=false test
• python3 scripts/plugins_repo.py validate

Notes

• this PR intentionally keeps the plugin version unchanged because this repository’s release metadata is managed from the default branch release flow
• the targeted tests were expanded and pass locally; I did not run the full reactor test suite because the focused notion module validation already covers the touched area