Add lap-gate settings and independent pit session automation #110

Parent: #105

Objective

Expose persistent device settings for selecting the repeating lap boundary and independently enabling pit-gate session automation, then apply accepted four-gate events to the session workflow without removing manual controls.

Scope

• Add a Start/Finish lap-boundary setting; default to Finish.
• Add independent Pit Exit Auto-Start and Pit Entry Auto-Stop enable/disable settings; both default disabled.
• Persist the three settings in a new versioned settings format and migrate v1-v3 data safely.
• Expose all three through Setup > Device Settings with explicit values and active-session locking.
• Map the selected boundary into TimingEngineConfig.
• Consume only accepted, typed pit gate events for automation.
• Pit exit may start only from Ready; pit entry may stop only Running/Overtime. Duplicate, rejected, disabled, or wrong-state events are no-ops.
• Automated pit entry completes the stop directly and records a distinct completion reason; guarded manual stop remains unchanged and always available.
• Emit deterministic automation decisions suitable for logging/diagnostics.

Acceptance criteria

• Saved values survive restart and v1-v3 settings migrate with safe defaults.
• Setup can change Start/Finish and both pit toggles only while inactive.
• Timing configuration uses exactly the saved lap boundary.
• Each pit toggle operates independently in replay tests.
• Accepted pit exit starts once from Ready; accepted pit entry stops once from Running/Overtime.
• Rejected, duplicate, disabled, and invalid-state events do not transition the session.
• Manual start and guarded manual stop tests remain green.
• Host, simulator, and ESP32-S3 firmware builds pass.