Adds read-only function tools: list_custom_nodes (packages, versions,
registered node types), list_custom_node_files, read_custom_node_file
(chunked by line) and search_custom_node_files. Paths stay inside one
package; hidden files, credential-like names and binaries are refused,
secret values are redacted. Tool budget raised to 20 calls / 8 rounds.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
