Add delete_block tool to remove blocks by UUID

[arndjan]

Summary

Adds support for deleting blocks via the logseq.Editor.removeBlock API method.

Changes

• Added delete_block(block_uuid) method to LogSeq class in logseq.py
• Added DeleteBlockToolHandler class in tools.py
• Registered the new tool handler in server.py

Usage

# MCP tool call
{
  "name": "delete_block",
  "arguments": {
    "block_uuid": "6983204d-ef32-4fbf-b19c-02181f16b28e"
  }
}

Motivation

Currently the MCP server supports creating and editing blocks, but not deleting them. This makes it impossible to clean up test blocks or remove unwanted content programmatically.

The underlying Logseq API already supports this via logseq.Editor.removeBlock, so this PR simply exposes that functionality.

Closes #14

🤖 Generated with Claude Code

[ergut]

Thanks @arndjan for this contribution! delete_block allows cleaning up blocks programmatically alongside the existing create/edit tools.

We made a small follow-up commit after merging to align the response messages with the conventions used in other handlers (emoji prefixes, ValueError catch branch). Nothing substantial, just keeping things consistent.