Deep Review: Full-Context Code Review + Fix

Performs a thorough code review with full PR/issue context, then fixes all actionable findings. Combines the depth of spec review, quality review, and Go-specific analysis in a single pass.

Step 0: Parse Arguments

Parse $ARGUMENTS to extract:

• Bare numeric value: PR number (e.g., $review-deep 42)
• --issue <N>: Use specific issue as context (no PR required)
• --post: Auto-post findings to PR as a comment (skip asking)
• --scope <hint>: Focus area for the review (e.g., "error handling", "concurrency")
• Remaining text after flags: treated as scope hint

Store as PR_ARG, ISSUE_ARG, AUTO_POST (default: false), SCOPE_HINT.