fix: rock-solid idle detection in respawn controller

- Add 300-char rolling window to catch working patterns split across PTY chunks
- Check completion message BEFORE working patterns (priority fix)
- Clear rolling window on completion message (transition point)
- Increase working pattern absence threshold from 3s to 8s
- Add Session.isWorking safety check before confirming idle
- Add 20+ more working patterns (Compiling, Building, Processing, etc.)
- Make AI idle checker prompt more conservative (err toward WORKING)
- Update documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/data-generator.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# Generates timestamped data to a file for testing
+# Usage: ./scripts/data-generator.sh [output_file] [interval_seconds]
+# Then: tail -f /tmp/test-data.log
+
+OUTPUT="${1:-/tmp/test-data.log}"
+INTERVAL="${2:-1}"
+
+echo "Writing to $OUTPUT every ${INTERVAL}s (Ctrl+C to stop)"
+echo "Run: tail -f $OUTPUT"
+
+i=0
+while true; do
+    ((i++))
+    echo "[$(date '+%Y-%m-%d %H:%M:%S')] Line $i - Random: $RANDOM" >> "$OUTPUT"
+    sleep "$INTERVAL"
+done