bug: authenticated Codex MCP probe fails on /mcp URL redirect

Describe the bug

The Codex MCP integration fails to discover the PowerContext tools when the configured Streamable HTTP URL is http://127.0.0.1:8000/mcp and the Server requires Bearer authentication. The canonical endpoint with a trailing slash, http://127.0.0.1:8000/mcp/, works correctly.

The failure is especially confusing because authorization itself can be configured correctly, while the native MCP probe still reports that remember_memory and search_memory are unavailable.

Steps to reproduce

1. Run PowerContext Server on Windows with enforced Bearer authentication and MCP enabled.
2. Configure the Codex integration with:
   http://127.0.0.1:8000/mcp
3. Set POWERCONTEXT_CODEX_AUTHORIZATION to a valid Bearer <token> value.
4. Restart Codex and run powercontext doctor codex.
5. Observe that authorization is reported as configured, but required MCP tools are not discovered.
6. Connect directly to http://127.0.0.1:8000/mcp/ and perform the MCP initialize and tools/list requests with the same credential.

Expected behavior

The generated Codex MCP configuration should use the canonical endpoint, or the Server/client combination should handle /mcp and /mcp/ equivalently while preserving the Authorization header. The native Codex probe should discover the PowerContext tools.

Actual behavior

The /mcp request is redirected to /mcp/. In the affected client path, the redirected request does not preserve the Authorization header and returns 401 Unauthorized. Using /mcp/ directly succeeds: MCP initialization completes and tools/list returns the expected tools, including remember_memory and search_memory.

Observed diagnostic state:

authorization: ok
current_process: configured
mcp tools: failed - Codex native MCP did not discover required tools: remember_memory, search_memory

Environment

• PowerContext: 3.4.4
• OS: Windows
• Transport: Streamable HTTP
• Server URL configured by the Codex integration: http://127.0.0.1:8000/mcp
• Working endpoint: http://127.0.0.1:8000/mcp/

Are you willing to submit a PR to fix this bug?

• Yes, I would like to submit a PR.

Start with the Codex integration that generates the MCP configuration and the code behind powercontext doctor codex; reproduce the probe using /mcp and /mcp/ with Bearer authentication. Done means the configured endpoint works through the redirect or uses the canonical trailing-slash URL, preserves authorization, and discovers remember_memory and search_memory.