Implement On-Balance Volume (OBV) Strategy

[cinar]

Implement the On-Balance Volume (OBV) trading strategy using the existing volume.Obv indicator.

Location: strategy/volume/obv_strategy.go

Strategy Rules:

• Buy Action: OBV crosses above its 10-period SMA (Simple Moving Average).
• Sell Action: OBV crosses below its 10-period SMA.
• Hold Action: Otherwise.

Implementation Details:

• Follow the strategy.Strategy interface.
• Use volume.NewObv() and trend.NewSmaWithPeriod(10) to calculate signals.
• Provide unit tests with historical data in strategy/volume/testdata/obv_strategy.csv.
• Ensure 100% test coverage.