fix(mse): validate NOTIONAL filter before placing buy order

SymbolFilters now parses minNotional from Binance NOTIONAL filter.
strategy.rs checks qty*price >= minNotional before market_buy,
returning a descriptive error instead of letting Binance reject with -1013.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/binance/client.rs

@@ -223,6 +223,7 @@ impl BinanceClient {
         let mut price_decimals = 2usize;
         let mut step_size = 0.01f64;
         let mut min_qty = 0.0f64;
+        let mut min_notional = 0.0f64;
 
         for filter in filters {
             match filter["filterType"].as_str() {
@@ -236,11 +237,14 @@ impl BinanceClient {
                     let tick = filter["tickSize"].as_str().unwrap_or("0.01");
                     price_decimals = count_decimals(tick);
                 }
+                Some("NOTIONAL") => {
+                    min_notional = filter["minNotional"].as_str().unwrap_or("0").parse().unwrap_or(0.0);
+                }
                 _ => {}
             }
         }
 
-        Ok(SymbolFilters { qty_decimals, price_decimals, step_size, min_qty })
+        Ok(SymbolFilters { qty_decimals, price_decimals, step_size, min_qty, min_notional })
     }
 
     /// Tüm USDT spot işlem çiftlerini döner — public endpoint, API key gerektirmez

src/binance/models.rs

@@ -52,6 +52,7 @@ pub struct SymbolFilters {
     pub price_decimals: usize,
     pub step_size: f64,
     pub min_qty: f64,
+    pub min_notional: f64,
 }
 
 impl SymbolFilters {
@@ -70,6 +71,9 @@ impl SymbolFilters {
     pub fn qty_is_valid(&self, qty: f64) -> bool {
         qty >= self.min_qty
     }
+    pub fn notional_is_valid(&self, qty: f64, price: f64) -> bool {
+        self.min_notional <= 0.0 || qty * price >= self.min_notional
+    }
 }
 
 /// Timeframe tanımları

src/bot/strategy.rs

@@ -38,6 +38,12 @@ impl RedCandleStrategy {
                 quantity, filters.min_qty
             ));
         }
+        if !filters.notional_is_valid(qty_f, kline.close) {
+            return Err(anyhow::anyhow!(
+                "İşlem tutarı ({:.2} USDT) min notional ({} USDT) altında — USDT miktarını artır",
+                qty_f * kline.close, filters.min_notional
+            ));
+        }
 
         info!("[{}] Market alım | Miktar: {} | Fiyat tahmini: {:.6}", symbol, quantity, kline.close);