Auto-resume flight across chunk unload/reload

When the ship's chunk unloads the CC computer powers off and its redstone
outputs reset to 0, so on return the ship dropped and the pilot had to
re-ENGAGE every time. Flight state now survives the reboot:

- engaged.txt flag written while flying, cleared on pilot STOP.
- On boot, if engaged + profile present: drive the hover baseline
  immediately (closes the fall gap), then runStandby(true) re-enters the
  flight loop automatically with the persisted target -- no manual ENGAGE.
- runFly drives hover before its first sleep so no entry path leaves a
  0-output gap.
- Cleanup no longer lifts a PARKED ship: Ctrl+T out of standby holds hover
  only when engaged, else valves off.
- engaged.txt registered as per-ship state (gitignore, installer keep/reset,
  menu reset, build excludes).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

install.lua

@@ -20,7 +20,7 @@ local BASE  = "https://gt.zyon.no/Stian/airship-autopilot/raw/branch/main"
 local ROLES = { "autopilot", "cockpit" }
 
 -- per-skip tilstand: roeres aldri automatisk, men tilbys nullstilt ved install
-local STATE_FILES = { "sides.txt", "calib.txt", "target.txt", "settings.txt" }
+local STATE_FILES = { "sides.txt", "calib.txt", "target.txt", "settings.txt", "engaged.txt" }
 
 -- kjente filer fra eldre versjoner som ikke lenger hoerer til rollen (engangs-rydding;
 -- videre oppdateringer ryddes automatisk via installasjons-loggen .installed_<role>)