docs: add core agent line count script and update README with real-time stats

core_agent_lines.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+# Count core agent lines (excluding channels/, cli/, providers/ adapters)
+cd "$(dirname "$0")" || exit 1
+
+echo "nanobot core agent line count"
+echo "================================"
+echo ""
+
+for dir in agent agent/tools bus config cron heartbeat session utils; do
+  count=$(find "nanobot/$dir" -maxdepth 1 -name "*.py" -exec cat {} + | wc -l)
+  printf "  %-16s %5s lines\n" "$dir/" "$count"
+done
+
+root=$(cat nanobot/__init__.py nanobot/__main__.py | wc -l)
+printf "  %-16s %5s lines\n" "(root)" "$root"
+
+echo ""
+total=$(find nanobot -name "*.py" ! -path "*/channels/*" ! -path "*/cli/*" ! -path "*/providers/*" | xargs cat | wc -l)
+echo "  Core total:     $total lines"
+echo ""
+echo "  (excludes: channels/, cli/, providers/)"