Secure hosted MCP credential setup

[hmishra2250]

Summary

Updates firecrawl setup mcp so hosted MCP credentials are carried through client-supported authorization configuration instead of being embedded in MCP URLs or subprocess command strings.

The CLI continues to target the keyless-first https://mcp.firecrawl.dev/v2/mcp endpoint. Browser account connection remains the responsibility of /v2/mcp-oauth, not the unattended CLI setup path.

What changed

• keyless setup remains available when no API key is configured;
• Codex uses bearer_token_env_var = "FIRECRAWL_API_KEY";
• header-capable clients receive environment-backed Bearer configuration;
• raw keys are not persisted into MCP URLs;
• subprocess launch uses argument arrays rather than secret-bearing shell strings;
• Hermes rejects stored raw-key setup before reading or mutating its config and accepts environment references safely;
• existing Hermes YAML is preserved and credential-bearing files use mode 0600 on POSIX;
• launcher and setup behavior remains compatible across supported agents.

Verification

• final local suite: 387 tests passed, with one intentional skip;
• TypeScript and package build passed;
• live CLI smoke verified Codex and Claude Code environment-reference configuration and confirmed raw keys were absent from captured child arguments;
• GitHub tests and Linux/macOS binary and package smokes passed on the final head;
• Windows binary testing passed, with the Windows package smoke running as part of the final CI matrix.

This PR contains no OAuth-server behavior and can publish after the reviewed runtime behavior is confirmed.