Add Parallel MCP setup skill with Bifrost support

[jliounis]

Summary

Adds parallel-mcp-setup for authenticated Parallel MCP installation, with Parallel Search MCP through Bifrost as the first supported setup path. The shared name allows additional setup paths to be added later. It activates for setup/configuration work; MCP-provided tool descriptions remain the source of search and fetch usage instructions.

The setup uses the authentication-required /mcp-oauth endpoint with a Bearer key or OAuth. It covers secret references, existing-connection handling, downstream tool access, and verification through Bifrost. It offers no anonymous/free setup path.

A supporting reference documents gateway-level Search controls: mode (the Search processing preset), source filters, result/excerpt budgets, location, and fetch policy. Setup preserves Parallel defaults by omitting search overrides. The reference explains opt-in x-parallel-search-config settings, URL parameter precedence, and configuration failure handling. The README lists the skill; existing builders package it for the catalog and release archives.

Validation

• All 28 existing Python tests pass.
• Markdown pre-commit checks pass.
• CDN site and release archive builds pass.
• JSON setup examples contain authentication only; mode and output limits are left at Parallel defaults. Markdown lint passes after the defaults-only revision.
• Authentication and configuration guidance checked against current Parallel and Bifrost documentation.

[sergei1152]

i'm not sure if a skill for using the mcp is needed (its already embedded in the mcp spec with tool descriptions). We should not rely on an llm to read both the skill + mcp tool description to use the mcp. If you think we need better tooling instructions, we can modify the mcp directly perhaps.

Ok if we want to have a plain parallel-mcp-setup skill to help setup the search & task mcp though across whatever agent you happen to be using.