Context7 should mirror `websearch` by only sending auth when
`CONTEXT7_API_KEY` is set.
Change: set bearer auth in `headers` using `CONTEXT7_API_KEY` if said environment variable is set, otherwise leave `headers` to `undefined`.
OpenCode's OAuth auto-detection was causing context7 and grep_app MCPs
to be disabled despite having enabled: true. Only websearch was working.
Root cause: Remote MCP servers trigger OAuth detection by default in
OpenCode, which can mark MCPs as 'needs_auth' or 'disabled' status
even when they don't require OAuth.
Fix: Add oauth: false to all 3 built-in MCP configs to explicitly
disable OAuth auto-detection. These MCPs either:
- Use no auth (context7, grep_app)
- Use API key header auth (websearch with EXA_API_KEY)
