fix(codexcli-mcp): strip empty env tables from generated config

[sirmacik]

Summary

The codex generator currently emits an empty [mcp_servers.X.env] header for any server whose env is {}. Codex CLI 0.130+ rejects this on remote (sse/http/streamable_http) transports with:

Error loading config.toml: env is not supported for streamable_http
in `mcp_servers.X`

This is a hard startup failure for any source mcp.json that has a remote MCP server with an empty env (intentionally, or left over from another tool's schema shape).

Repro

// .rulesync/mcp.json
{
  "mcpServers": {
    "aws-knowledge": {
      "type": "sse",
      "url": "https://knowledge-mcp.global.api.aws",
      "env": {}
    }
  }
}

After rulesync generate -g:

[mcp_servers.aws-knowledge]
type = "sse"
url = "https://knowledge-mcp.global.api.aws"

[mcp_servers.aws-knowledge.env]   ← codex rejects this

Fix

Make removeEmptyEntries in codexcli-mcp.ts recursive so empty nested objects (env: {}) are stripped at any depth, not just at the top level. Arrays are preserved verbatim because an empty array can be a meaningful explicit override.

Side effect: stdio servers also get cleaner output (no more inert empty [mcp_servers.X.env] headers). Codex tolerates those, so this is purely cosmetic for stdio.

Tests added

• should strip empty env object from remote (sse) server — repro test
• should strip empty env object from stdio server (clean output)
• should preserve populated env table on stdio server

All 54 codex MCP tests pass. pnpm cicheck is clean.

Risk

Minimal — recursing into nested objects is a generalization of the existing behaviour (which already strips empty top-level server configs). No existing test relied on empty env: {} being preserved inside a server config.

[dyoshikawa]

@sirmacik Thank you!