UNIFY: one exe -- retire the pod/glass/steam compile split

The three build dirs (build\ pod, build-glass\, build-steam\) were compile-
time splits of the same game; the tax was real: a stale steam exe shipped 2
days behind, the felt keymap flipped with the boot flavor, and cockpit
clicks were silently dead in the pod build (the trigger-config incident).

Now everything compiles into the single build\ exe:
- CMakeLists: BT_GLASS/BT_STEAM options removed; the glass TUs (PadRIO,
  bindings, panel, glass windows, plasma) + FE/console + Steam transport
  compile unconditionally; both macros always defined (seam markers).
- Steam: steam_api.lib linked with /DELAYLOAD:steam_api.dll + delayimp --
  the DLL maps only when SteamAPI is first called, and every call site
  gates on BT_STEAM_NET=1 (BTSteamNet_* short-circuit on steamActive), so
  machines without the DLL run everything but Steam sessions.
- CABINET GUARD (btl4main): the miniconsole menu previously claimed any
  zero-arg launch -- unified, that would hijack the pod cabinet's boot
  shape.  The menu now requires BT_PLATFORM=glass (or BT_FE_MENU=1);
  platform parse moved above the fe_menu_mode computation.  A bare boot
  behaves exactly like the old pod build (DEV profile, wait for egg).
- Bats (play_solo/join/join_lan/play_steam) + the btoperator.py template:
  single build\ path + BT_PLATFORM=glass.  mkdist: one exe (+DLL scan
  picks up OpenAL32 + steam_api).  build-glass\/build-steam\/build-glass2\
  (a stale Jul-20 cache) deleted.

Verified matrix on the unified exe:
  bare zero-arg boot == old pod exe (same DEV profile + egg-load path;
    the segfault on a missing egg is pre-existing, baselined vs the zip exe)
  glass + BT_BTNTEST scripted click -> [cfgmap] ENTER/EXIT (trigger config)
  runs with steam_api.dll ABSENT (delay-load proven)
  glass zero-arg -> miniconsole menu
  2-node loopback MP: 145 ticks each, cross-connected
  BT_STEAM_NET=1 without Steam client -> "staying on Winsock", game runs

KB: context/glass-cockpit.md compile-gates section rewritten for the
unified model.

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

players/join.bat

@@ -2,23 +2,18 @@
 rem BT411 -- join 107.202.218.169's game (internet).  Seat/mech assigned
 rem by the operator.  Keep this file next to content\ + build\.
 cd /d %~dp0
-rem Prefer the GLASS build when present (dev checkout): PadRIO makes the
-rem cockpit surround's buttons mouse-clickable (trigger config etc.).  The
-rem pod build renders the same cockpit but clicks are a no-op there; player
-rem zips ship only build\.
-set GAME=build\Release\btl4.exe
-if exist "build-glass\Release\btl4.exe" (
-  set GAME=build-glass\Release\btl4.exe
-  set BT_PLATFORM=glass
-)
-if not exist "%GAME%" goto badpath
+rem ONE unified build (2026-07-21): the exe carries every layer; the GLASS
+rem platform env arms the desktop cockpit (clickable MFD buttons, trigger
+rem config, bindings.txt keymap).
+set BT_PLATFORM=glass
+if not exist "build\Release\btl4.exe" goto badpath
 if not exist "content\OPERATOR.EGG" goto badpath
 set BT_RELAY=107.202.218.169:1500
 set BT_LOG=join.log
 set BT_START_INSIDE=1
 set BT_DEV_GAUGES=1
 cd content
-..\%GAME% -egg OPERATOR.EGG -net 1501
+..\build\Release\btl4.exe -egg OPERATOR.EGG -net 1501
 echo.
 echo The game has exited.  If you did NOT quit on purpose
 echo (crash, or it never connected), send the operator the