Add controller test suite and reach 72 percent line coverage

Cover control map capacity, the default binding set, keyboard and gamepad
dispatch including cross-device rejection, the dpad handlers, and device
add and remove against the dummy SDL drivers. Synthesize SDL events directly
rather than pumping the event queue, so the suite needs no real hardware.

Fix the three-way appstate check in the four gamepad handlers, which tested
appstate in place of both the event pointer and the looked-up player actor,
so a null event or a missing player was dereferenced instead of reported.

Record the new coverage status in TODO.md along with the seven defects the
suites uncovered and fixed, eleven that remain open, and the reason the
build tree has to precede LD_LIBRARY_PATH for the CTest run.

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

CMakeLists.txt

@@ -127,6 +127,7 @@ set(AKGL_TEST_SUITES
   actor
   bitmasks
   character
+  controller
   game
   heap
   json_helpers