Extend DA MCP to support advanced search capabilities

As an author, I need the ability to search and filter pages based on metadata and content criteria to improve content discoverability and management. I want to search for pages using specific filgers, so that I can quickly locate relevant content without manual browsing.

Currently, the DA MCP lacks granular search capabilities, making it difficult to manage large content repositories efficiently.

First acceptance criteria (based on first feedback during demo and using the product myself)
- Filter pages by creation or last modified date (e.g., since `YYYY-MM-DD`)
- Filter pages by authors (creator or last modifier)
- Full-text search (e.g. contains certain blocks or text)
- Bonus: Semantic search