Add AI generated cap-band strategy example

data/demo/ai_generated_000001_open_cap_band.engine-script.txt

@@ -0,0 +1,42 @@
+let refresh_rate = 15;
+let stocknum = 40;
+let xs = 0.008;
+let base_index_level = 2000;
+let lower_offset = 3;
+let upper_offset = 28;
+
+fn cap_floor(current_price, base_index_level, xs, lower_offset) {
+round((current_price - base_index_level) * xs + lower_offset)
+}
+
+fn cap_ceiling(current_price, base_index_level, xs, upper_offset) {
+round((current_price - base_index_level) * xs + upper_offset)
+}
+
+strategy("ai_generated_000001_open_cap_band") {
+market("CN_A")
+benchmark("000852.SH")
+signal("000001.SH")
+
+rebalance.every_days(refresh_rate).at("10:18")
+
+universe.exclude("paused", "st", "kcb", "one_yuan", "new_listing")
+
+selection.limit(stocknum)
+selection.market_cap_band(
+field="market_cap",
+lower=cap_floor(signal_open, base_index_level, xs, lower_offset),
+upper=cap_ceiling(signal_open, base_index_level, xs, upper_offset)
+)
+
+filter.stock_expr(
+stock_ma5 > stock_ma10 &&
+stock_ma10 > stock_ma30 &&
+rolling_mean("volume", 5) < rolling_mean("volume", 60) &&
+!ends_with(symbol, ".BJ") &&
+!at_upper_limit &&
+!at_lower_limit
+)
+
+  ordering.rank_by("market_cap", "asc")
+}