Deduplicate the host audio/UI code and scrub history from comments

Extract a RAII RenderEndpoint that owns the enumerator/endpoint/client/
render-event/buffer for both AudioMirror::run_hooked and run_loopback,
replacing two hand-rolled setup+teardown blocks and their two identical
fail lambdas with one set_error helper; every COM object now frees on
each exit path automatically.

Route audio_format_verifier's mono decode through the shared
correlate_detail::decode_layout instead of a second copy, and read the
debug env var via GetEnvironmentVariableA (drops the getenv C4996).

Fold the near-identical read_frame/read_pixel staging-copy setup in
SharedTextureSource into one map_staging_copy, and the three separate
case-insensitive filter helpers (log/injection panels) into
ui/text_match.hpp.

Comments: drop game-name anecdotes and "the old code"/version phrasing;
genericize the override-file example; fix a stale heartbeat-interval
note. Behavior unchanged (host tests + mock_game_test pass).

host/src/audio/audio_overrides.hpp

@@ -5,8 +5,8 @@
 // truth). A human-readable one-line-per-game text file:
 //
 //   # CoopAllTheThings per-game audio overrides
-//   brotato.exe = 44100 2 32 float
-//   snb.exe = 48000 2 16 pcm
+//   <image.exe> = 44100 2 32 float
+//   <image.exe> = 48000 2 16 pcm
 #pragma once
 
 #include <cstdint>