Make serial port settle delay configurable

[Copilot]

Addresses hard-coded 10ms sleep after serial port configuration in configureTermios. The delay lacks documentation and cannot be adjusted for different hardware requirements or performance-sensitive applications.

Changes:

• Added SettleDelay field to SerialConfig with behavior:
  • Zero value (unset) → defaults to 10ms for backward compatibility
  • Positive value → uses specified duration
  • Negative value → disables delay entirely
• Documented why the delay exists (hardware stabilization after terminal reconfiguration)
• Updated configureTermios to use configurable delay parameter

Usage:

// Use default 10ms delay
cfg := drivers.SerialConfig{Port: "/dev/ttyUSB0", Baud: 9600}

// Custom delay for specific hardware
cfg := drivers.SerialConfig{
    Port: "/dev/ttyUSB0", 
    Baud: 9600,
    SettleDelay: 50 * time.Millisecond,
}

// Disable delay for performance-sensitive applications
cfg := drivers.SerialConfig{
    Port: "/dev/ttyUSB0", 
    Baud: 9600,
    SettleDelay: -1,
}

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[Copilot]

Pull request overview

This PR makes the serial port settle delay configurable by adding a SettleDelay field to SerialConfig. The previously hard-coded 10ms delay after terminal configuration can now be customized or disabled based on hardware requirements.

Changes:

• Added SettleDelay field to SerialConfig with documentation explaining its purpose and behavior (zero defaults to 10ms, negative disables)
• Updated configureTermios to accept and apply the configurable settle delay
• Cleaned up unused dependencies from go.mod and go.sum

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
drivers/serial.go	Added SettleDelay field to SerialConfig with clear documentation
drivers/serial_linux.go	Updated configureTermios signature and implementation to use configurable delay
go.mod	Promoted golang.org/x/sys to direct dependency, removed unused dependencies
go.sum	Synchronized with go.mod changes

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[Copilot]

The promotion of golang.org/x/sys from an indirect to a direct dependency is appropriate since it's imported directly in drivers/serial_linux.go. However, the removal of github.com/maciej/bme280, github.com/nfnt/resize, and golang.org/x/image appears unrelated to the stated PR purpose of making the serial port settle delay configurable. Consider separating dependency cleanup into a separate PR for clearer change tracking.