Type at the window with a real keyboard: the akgl_typing test

xdotool closes the gap that shipped the missing SDL_StartTextInput(). Every
other keyboard test synthesises SDL events, which covers the code downstream
of SDL and cannot cover the code upstream of it -- so the suite stayed green
while the real keyboard was dead.

akgl_typing starts the driver under a pty, waits for the window with xdotool
search --sync, gives it focus, and types a program containing a string literal
and a lower-case one, polling the mirrored stdout for what they print. Verified
by reverting both halves of the text-input fix and watching it fail with the
reported symptom: READY, and nothing after it.

Skips rather than fails without a display, xdotool, script(1) or a window
manager -- none of those means the answer is no. It steals keyboard focus for
about fifteen seconds; AKBASIC_SKIP_INTERACTIVE=1 skips it deliberately.

xdotool and script(1) are documented as optional test dependencies, alongside
what gcovr and python3 already bought.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -214,6 +214,11 @@ jobs:
       # they are the ones that must keep passing when SDL is present, *and* they
       # are what proves the SDL frontend changes no output anywhere in the
       # corpus.
+      # akgl_typing reports Skipped here and that is correct: it needs a real X
+      # server, a window manager and xdotool to type at a focused window, and a
+      # CI runner has none of the three. It is a developer-machine gate, and the
+      # one that covers the path upstream of SDL -- see its script for why that
+      # distinction cost a bug once.
       - name: test with libakgl
         env:
           SDL_VIDEODRIVER: dummy