Preserve relative-alt guided behavior by setting Locationwp.frame at implicit callers

[Copilot]

A recent guided-mode path change surfaced a behavior shift: callers constructing Locationwp without frame now send default GLOBAL (AMSL) instead of the previously normalized relative-alt behavior. For Copter paths passing relative altitude, this can produce unintended altitude commands.

• Scope: explicit frame assignment at affected guided callers

  • Added frame = (byte)MAVLink.MAV_FRAME.GLOBAL_RELATIVE_ALT where Locationwp was built with lat/lng/alt only before setGuidedModeWP(...).
  • Updated call sites:
    • Controls/FollowMe.cs
    • Utilities/httpserver.cs (/guide GET + POST handlers)
    • Swarm/FollowPath.cs
    • ExtLibs/ExtGuided/ExtGuidedPlugin.cs
    • Plugins/example14-mass.cs
    • ExtLibs/Xamarin/Xamarin/Linked/httpserver.cs (mirrored HTTP guided handlers)

• Behavioral intent

  • Restore pre-change semantics for these paths by making altitude frame explicit.
  • Keep existing FlyToHere / GuidedMode.frame-threaded paths untouched.

var gwp = new Locationwp
{
    lat = ...,
    lng = ...,
    alt = ...,
    frame = (byte)MAVLink.MAV_FRAME.GLOBAL_RELATIVE_ALT
};
MainV2.comPort.setGuidedModeWP(gwp);