feat(grid): auto-adjust grid direction based on box breakouts

Add GridDirection type with 5 states:
- neutral (50% buy + 50% sell)
- long/short (100% one direction)
- long_bias/short_bias (70%/30% configurable)

Direction adjustment logic:
- Short box breakout → bias direction (long_bias/short_bias)
- Mid box breakout → full direction (long/short)
- Long box breakout → emergency handling (unchanged)
- Recovery: long → long_bias → neutral ← short_bias ← short

Config options:
- EnableDirectionAdjust (default: false)
- DirectionBiasRatio (default: 0.7)

Includes unit tests for all direction-related functions.

store/grid.go

@@ -63,6 +63,10 @@ type GridConfigModel struct {
 	AIProvider string `json:"ai_provider" gorm:"default:deepseek"`
 	AIModel    string `json:"ai_model" gorm:"default:deepseek-chat"`
 	IsActive   bool   `json:"is_active" gorm:"default:false"`
+
+	// Direction adjustment settings
+	EnableDirectionAdjust bool    `json:"enable_direction_adjust" gorm:"default:false"`
+	DirectionBiasRatio    float64 `json:"direction_bias_ratio" gorm:"default:0.7"`
 }
 
 func (GridConfigModel) TableName() string {
@@ -108,6 +112,11 @@ type GridInstanceModel struct {
 	// Position adjustment due to breakout
 	PositionReductionPct float64 `json:"position_reduction_pct" gorm:"default:0"` // 0 = normal, 50 = reduced
 
+	// Grid direction adjustment state
+	CurrentDirection       string    `json:"current_direction" gorm:"default:neutral"`
+	DirectionChangedAt     time.Time `json:"direction_changed_at"`
+	DirectionChangeCount   int       `json:"direction_change_count" gorm:"default:0"`
+
 	TotalProfit     float64   `json:"total_profit" gorm:"default:0"`
 	TotalFees       float64   `json:"total_fees" gorm:"default:0"`
 	TotalTrades     int       `json:"total_trades" gorm:"default:0"`

store/strategy.go

@@ -81,6 +81,10 @@ type GridStrategyConfig struct {
 	DailyLossLimitPct float64 `json:"daily_loss_limit_pct"`
 	// Use maker-only orders for lower fees
 	UseMakerOnly bool `json:"use_maker_only"`
+	// Enable automatic grid direction adjustment based on box breakouts
+	EnableDirectionAdjust bool `json:"enable_direction_adjust"`
+	// Direction bias ratio for long_bias/short_bias modes (default 0.7 = 70%/30%)
+	DirectionBiasRatio float64 `json:"direction_bias_ratio"`
 }
 
 // PromptSectionsConfig editable sections of System Prompt