Merge BT411 audio-fidelity + combat work (4e72f0c..abed41e) into BT412

Brings the post-fork BT411 line forward via a local-path merge (never
touches the BT411 gitea remote): the full audio-fidelity system (engine
AUD*/L4AUD* + audiopresets.cpp + ~600 content wavs + AUDIO_FIDELITY.md),
missiles/rear-fire/HUD/gyro/gait tasks (#66-68), FOGDAY.EGG, and
refreshed context docs -- 91 commits, ~688 files clean.

Only 5 files overlapped the steamification; resolved keeping BOTH:
- L4NET.CPP: took BT411's task-#50 fix (don't close the game listener on
  console loss) over the seam's adaptation of the old buggy close; sends
  stay on NetTransport_Get().
- L4NETTRANSPORT.cpp: folded BT411's TCP_NODELAY latency fix into
  WinsockNetTransport::Connect (the seam already had retry + nonblocking).
- mechmppr.cpp: combined the device_owns_input gating with BT411's
  task-#68 look-behind, gating the lookBehind write too.
- .gitignore / CMakeLists.txt / mech4.cpp: trivial / auto-merged
  (deviceOwnsInput gating preserved).

Verified: clean build (default + implicitly the Steam TU untouched);
solo front-end mode; loopback MP through the seam (mesh completes, both
tick, replication works, no NODELAY warnings).

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

.gitignore

@@ -14,6 +14,7 @@ cdb_*.txt
 .vs/
 *.user
 Thumbs.db
+__pycache__/
 
 # per-user input profile, written by the game on first PAD run (cwd=content)
 /content/bindings.txt

CMakeLists.txt

@@ -164,7 +164,12 @@ add_library(munga_engine STATIC
   "engine/MUNGA/TERRAIN.cpp"
   "engine/MUNGA/TESTALL.cpp"
   "engine/MUNGA/TIME.cpp"
-  "engine/MUNGA/TIMESTUB.cpp"
+  # TIMESTUB.cpp REMOVED (2026-07-14): its GetRTC/GetHiRes were 2007 call-counter
+  # stubs (`return time++` -- the "clock" advanced per CALL, not per ms) that WON
+  # the /FORCE duplicate-symbol race over the REAL QueryPerformanceCounter clock
+  # in L4TIME.cpp (LNK4006 "second definition ignored").  Every Now()-domain
+  # consumer (dead-reckoning above all) ran on call-count pseudo-time -> the
+  # replicant stall/jump chop.  L4TIME.cpp covers every symbol TIMESTUB defined.
   "engine/MUNGA/TOOL.cpp"
   "engine/MUNGA/TRACE.cpp"
   "engine/MUNGA/TRACSTUB.cpp"
@@ -181,6 +186,7 @@ add_library(munga_engine STATIC
   "engine/MUNGA/WRHOUS.cpp"
   "engine/MUNGA_L4/DXUtils.cpp"
   "engine/MUNGA_L4/L4APP.cpp"
+  "engine/MUNGA_L4/L4AUDEFX.cpp"
   "engine/MUNGA_L4/L4AUDHDW.cpp"
   "engine/MUNGA_L4/L4AUDIO.cpp"
   "engine/MUNGA_L4/L4AUDLVL.cpp"
@@ -308,6 +314,7 @@ add_library(bt410_l4 STATIC
   "game/reconstructed/thermalsight.cpp"
   "game/reconstructed/torso.cpp"
   "game/reconstructed/btstubs.cpp"
+  "game/reconstructed/audiopresets.cpp"
   "game/reconstructed/dpl2d.cpp"
   "game/original/BT/BTMSSN.CPP"
   "game/original/BT/BTREG.CPP"
@@ -346,7 +353,6 @@ target_link_libraries(btl4 PRIVATE
     bt410_l4
     munga_engine
     "${CMAKE_SOURCE_DIR}/engine/lib/OpenAL32.lib"
-    "${CMAKE_SOURCE_DIR}/engine/lib/libsndfile-1.lib"
     "${DXSDK}/Lib/x86/d3d9.lib"
     "${DXSDK}/Lib/x86/d3dx9.lib"
     "${DXSDK}/Lib/x86/dinput8.lib"
@@ -372,9 +378,10 @@ if(BT412_STEAM)
             "$<TARGET_FILE_DIR:btl4>")
 endif()
 
-# Copy the third-party runtime DLLs next to the built exe.
+# Copy the OpenAL runtime DLL next to the built exe.  (libsndfile is gone: its
+# repo DLL was a no-op STUB -- L4AUDRES now loads the soundbank WAVs with an
+# in-tree RIFF/PCM reader, no external dependency.)
 add_custom_command(TARGET btl4 POST_BUILD
     COMMAND ${CMAKE_COMMAND} -E copy_if_different
         "${CMAKE_SOURCE_DIR}/engine/lib/OpenAL32.dll"
-        "${CMAKE_SOURCE_DIR}/engine/lib/libsndfile-1.dll"
         "$<TARGET_FILE_DIR:btl4>")