Sign test: measure ALL gimbal axes + self-healing altitude supervisor; link diagnostics

- Sign test measures rate response on every gimbal axis and picks the one
  that actually answers the differential push -> pitchIndex is now MEASURED
  per ship (build orientation no longer matters). Verified both-direction
  response accepted at half threshold. Tilt guard watches all axes.
- Altitude supervisor: drifting out of the measuring band re-centers and
  retries instead of aborting; single 7-min deadline. Faster hover trim
  (0.05 -> 0.12, matches verified Ki_climb) plus an 8 s settle phase.
- Single-balloon ships: sign test marks itself done, FLY zeroes u_diff.
- Cockpit terminal now explains link status (OFFLINE checklist); autopilot
  standby screen warns loudly when no modem is attached.
- Failure text points at cross-wired links (both burners firing on one pulse).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

files/cockpit/cockpit.lua

@@ -151,6 +151,34 @@ local function draw()
   if page == "settings" then drawSettings() else drawStatus() end
 end
 
+-- terminal-diagnostikk: monitoren viser pilot-UI, terminalen FORKLARER link-status --
+-- "OFFLINE" skal aldri vaere et mysterium (vanligste aarsak: AP-PCen er ikke i standby/fly)
+local function drawTerm()
+  term.clear(); term.setCursorPos(1, 1)
+  print("==== COCKPIT CONSOLE ====")
+  print(string.format("Monitor %dx%d   modem: open", W, H))
+  print("")
+  if online() then
+    local s = status
+    print(string.format("Link: ONLINE (heartbeat %.1fs ago)", now() - lastRx))
+    print("State: " .. tostring(s.state)
+      .. ((s.reason and s.reason ~= "") and (" (" .. tostring(s.reason) .. ")") or ""))
+    print(string.format("Height %.1f -> %.0f   Pitch %+.1f", s.height or 0, s.target or 0, s.pitch or 0))
+    print(s.ready == false and "AP needs setup (wizard on the AP PC)" or "Control via the monitor buttons.")
+  else
+    print("Link: OFFLINE -- no heartbeat from the")
+    print("machine-room PC. Checklist over there:")
+    print(" 1) It must be in STANDBY or FLY mode")
+    print("    (menu/setup/shell do NOT broadcast)")
+    print(" 2) It needs a modem attached -- its")
+    print("    standby screen shows 'Link: modem OK'")
+    print(" 3) Wireless out of range? Use wired")
+    print("    modems + network cable instead.")
+  end
+  print("")
+  print("CTRL+T = quit")
+end
+
 local function handleTouch(x, y)
   for _, b in ipairs(buttons) do
     if x >= b.x1 and x <= b.x2 and y >= b.y1 and y <= b.y2 then b.action(); draw(); return end
@@ -158,6 +186,7 @@ local function handleTouch(x, y)
 end
 
 draw()
+drawTerm()
 local redraw = os.startTimer(0.5)
 while true do
   local e = { os.pullEvent() }
@@ -166,6 +195,6 @@ while true do
   elseif e[1] == "monitor_touch" then
     handleTouch(e[3], e[4])
   elseif e[1] == "timer" and e[2] == redraw then
-    redraw = os.startTimer(0.5); draw()
+    redraw = os.startTimer(0.5); draw(); drawTerm()
   end
 end