Streamline and verify documentation

[shanev]

Summary

• consolidate overlapping documentation into a task-based structure
• remove obsolete and experimental Verifiers and MCP HTTP material
• align protocol references with current runtime constants
• add automated checks for version drift, broken links, index reachability, and the embedding example

Validation

• uv run pytest -q
• uv run ruff check src tests examples/embedding.py
• uv run ruff format --check src tests examples/embedding.py
• uv build