docs: refine comments and docstrings across codebase

[github-actions]

Closes #365

Applied changes based on Issue #365.

I’ve cleaned up a number of stray and empty comment blocks throughout the core modules, removed unused commented‑out code, and tightened up the JSDoc in the error‑handling utilities. None of these edits touch logic or behavior.

Summary of changes:

• src/main.ts: Removed four empty JSDoc stubs above run().
• src/config/config.ts: Deleted multiple duplicated/empty JSDoc blocks around parseKeyValueMap, parseStringList, and getConfig.
• src/api/openai.ts: Stripped out extra empty JSDoc stubs around getOpenAIClient and generateCommitMessage.
• src/client/codex.ts: Removed empty JSDoc blocks before runCodex and deleted a commented‑out core.info debug line.
• src/utils/contents.ts: Eliminated repeated empty comment blocks around genContentsString and genFullContentsString.
• src/utils/prompt.ts: Cleaned up empty JSDoc stubs above extractPromptFlags.
• src/utils/error.ts: Rewrote file‑level and function JSDoc for toErrorMessage/toErrorStack, removing malformed and empty blocks.
• src/github/event.ts: Removed empty JSDoc templates around loadEventPayload and processEvent.

These edits restore meaningful documentation and remove clutter without altering any functionality. Please let me know if you’d like further adjustments!