feat: add sendToClaude helper and wait-for-event tool

- Add sendToClaude() function to browser helper that shows confirmation
- Add wait-for-event.sh script for watching server output (tail -f | grep -m 1)
- Enables clean event-driven loop: background bash waits for event, completion triggers Claude's turn

lib/brainstorm-server/wait-for-event.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+# Wait for a browser event from the brainstorm server
+# Usage: wait-for-event.sh <output-file> [event-type]
+#
+# Blocks until a matching event arrives, then prints it and exits.
+# Default event type: "send-to-claude"
+
+OUTPUT_FILE="${1:?Usage: wait-for-event.sh <output-file> [event-type]}"
+EVENT_TYPE="${2:-send-to-claude}"
+
+if [[ ! -f "$OUTPUT_FILE" ]]; then
+  echo "Error: Output file not found: $OUTPUT_FILE" >&2
+  exit 1
+fi
+
+# Wait for new lines matching the event type
+# -n 0: start at end (only new content)
+# -f: follow
+# grep -m 1: exit after first match
+tail -n 0 -f "$OUTPUT_FILE" | grep -m 1 "$EVENT_TYPE"