[codex] Hot-reload DeepSeek connection config

[Star-Star66]

Summary

• watch ~/.carboncode/config.json for DeepSeek API key and base URL changes
• apply connection changes only while the loop is idle, preserving the active session and transcript
• update the main loop, context folding, balance/model refreshes, and future subagents to use the replacement client
• preserve explicit environment-variable overrides and ignore partially written JSON

Why

Issue #95 notes that changing provider connection settings currently requires restarting Carbon Code. The TUI constructed one DeepSeekClient at startup, and both context folding and the subagent closure retained that original client.

This change atomically replaces the client after the current turn finishes, so dashboard or config-file edits take effect within about one second without losing conversation state.

Addresses the configuration hot-reload suggestion in #95 without closing the broader issue.

Validation

• npm run verify
• 340 test files passed
• 3918 tests passed, 2 skipped

[Cyberforker]

Review Summary

Reviewed & merged by Carbon Code

Tests: npm run verify - 3918/3918 passed, 2 skipped
Feat: hot-reload DeepSeek API key and base URL changes while the loop is idle, preserving active sessions and env override precedence.

Thanks @Star-Star66 for the clean client-replacement architecture and thorough config reload coverage.

Co-Authored-By: Carbon Code carboncode@code.ai6666.com

-- Carbon Code