fix(guardrails): tighten bash mut regex to reduce false review_state resets

[terisuke]

Background

PR #139 review finding [WARN-2]: The mut array regex />/ matches any command containing >, including benign uses like echo "version > 2" or commands with > inside quoted strings.

PR #139 amplified this by adding review_state reset on mutating bash commands (line 1024). Now harmless commands can falsely invalidate review state.

Fix

Tighten the > pattern to only match file redirects, not > inside quotes:

• Option A: />(?!\s*&)(?!\s*\/)(?!.*['"].*>.*['"])/ — exclude fd redirects and quoted strings
• Option B: Use a simple heuristic — split on unquoted |/&&/; first, then check each segment

Acceptance Criteria

• echo "version > 2" does NOT trigger mut detection
• gcloud list --format=json 2>&1 does NOT trigger mut detection
• echo test > file.txt DOES trigger mut detection
• sed -i 's/old/new/' file DOES trigger mut detection
• Tests for false positive and true positive cases

Source

PR #139 review comment [WARN-2], pre-existing amplified by review_state reset