fix: prevent duplicate CLI flags in buildAgentArgs

[jeffscottward]

Summary

• deduplicate repeated flag-style args in buildAgentArgs() while preserving order
• only deduplicate flags (-/--), leaving positional args unchanged
• add regression tests for the Codex duplicate bypass flag case and positional-arg safety

Why

When both batch mode and YOLO mode contribute the same flag (for example Codex --dangerously-bypass-approvals-and-sandbox), the final argv can contain duplicates and Codex exits with code 2.

Fixes #398

Follow-up Fix (Wizard/Codex)

• fix wizard conversation output selection for Codex when multiple agent_message events occur in one turn
• keep the latest Codex result text and emit at turn completion instead of taking the first interim message
• add regression test in StdoutHandler.test.ts to ensure only the final Codex message is emitted

This addresses cases where Wizard got stuck showing interim text like "I’m checking the directory..." instead of the actual final answer.

[jeffscottward]

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OIDC error on claude review. Config error?

[jeffscottward]

Added follow-up commit for Wizard/Codex behavior:

• ensure Codex multi-message turns emit the final response (not interim "I’m checking...")
• added regression test coverage in StdoutHandler tests

Commit: 2fa8dd2