feat(tier2): add post-checkout detection hook (logs to tier2_checkout_log.txt)

conductor/tier2/githooks/post-checkout

@@ -0,0 +1,13 @@
+#!/bin/sh
+# Tier 2 autonomous mode: detect (not prevent) any `git checkout` of tracked files.
+# Layer 1 (OpenCode permission) is the primary defense; this is a logging backup.
+
+LOG_DIR="${LOCALAPPDATA:-$HOME/.local/share}/manual_slop/tier2"
+LOG_FILE="$LOG_DIR/tier2_checkout_log.txt"
+mkdir -p "$LOG_DIR" 2>/dev/null || true
+
+COMMIT=$(git rev-parse HEAD 2>/dev/null || echo "unknown")
+TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ" 2>/dev/null || date -u)
+echo "[$TIMESTAMP] checkout detected: $COMMIT, files: $*" >> "$LOG_FILE" 2>/dev/null || true
+
+exit 0