fix(devin): keep Codex core tools and unstick Deepseek compact

[caigee-cmd]

Summary

• Neutralize Codex/Desktop MCP-looking Devin tools into reversible cx_tool_* aliases and restore original names on tool calls.
• If Devin still returns MCP configuration permission_denied, fall back to core local tools (exec_command / write_stdin / view_image / request_user_input) and log each fallback stage instead of dropping all tools.
• Ignore orphan tool_choice when Codex compact/recovery turns send a choice with no remaining tools.
• Stop session affinity from pinning a later model onto an empty-catalog account, so Deepseek compact after a Devin turn routes to WorkBuddy.

Test plan

• go test ./internal/providers/devin ./internal/translate ./internal/executor ./internal/accounts ./internal/api
• Re-run Codex compact on devin/gpt-5-6-sol and deepseek-v4.1-flash
• Confirm Devin MCP denials keep exec_command available and emit devin mcp fallback logs