Complete V2 autopilot provider API (route, dodge, gybe, mode, actions)

[motamman]

Summary

Completes the V2 autopilot provider API by implementing all previously stubbed methods and adding route mode support across all backends.

Route mode

• Added route as a valid autopilot state in the emulator, Raymarine N2K, and SeaTalk NG backends
• putAdjustHeading now accepts route mode in all three backends
• Emulator emits heading target and initializes current heading when entering route mode

Mode and state fixes

• getMode / setMode now functional — Raymarine/Simrad conflate mode and state, so setMode validates and delegates to putStatePromise
• setTarget falls back to apData.state when apData.mode is null
• engage immediately updates apData.state and apData.mode
• State change handler syncs apData.mode = apData.state

Dodge

• Full dodge implementation: saves pre-dodge state and target, switches route to auto, decomposes heading adjustments into ±10° and ±1° keystrokes, restores original state/target on cancel

Gybe, tack, and waypoint operations

• gybe delegates to putTackPromise (Raymarine uses the same keystroke; the pilot decides based on wind angle)
• courseCurrentPoint engages route mode to steer to the active waypoint
• courseNextPoint calls putAdvanceWaypoint and advances the SignalK course API point index
• Emulator putTack and putAdvanceWaypoint now validate state and input instead of returning "Unsupported"

Dynamic actions

• buildActions() computes available UI actions (tack, gybe, advance waypoint, steer to waypoint, dodge) based on current state and dodge status
• State changes broadcast updated actions to clients via app.autopilotUpdate