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/log_panel.cpp

@@ -1,37 +1,16 @@
 #include "log_panel.hpp"
 
-#include <algorithm>
-#include <cctype>
 #include <cstdio>
-#include <cstring>
-#include <string>
 
 #include "imgui.h"
 
 #include "injection_panel.hpp"
 #include "ui/app_chrome.hpp"
+#include "ui/text_match.hpp"
 
 namespace coop
 {
 
-namespace
-{
-// Case-insensitive substring test, so the log filter matches regardless of case (consistent with the
-// rest of the app, where "error" should find "ERROR").
-bool icontains(const std::string& hay, const char* needle)
-{
-	if (needle == nullptr || needle[0] == '\0')
-	{
-		return true;
-	}
-	auto lower = [](std::string s) {
-		std::transform(s.begin(), s.end(), s.begin(), [](unsigned char c) { return static_cast<char>(std::tolower(c)); });
-		return s;
-	};
-	return lower(hay).find(lower(needle)) != std::string::npos;
-}
-} // namespace
-
 void LogPanel::add_line(const LogRecord& rec)
 {
 	if (first_millis_ == 0)
@@ -76,7 +55,7 @@ void LogPanel::draw()
 		const bool has_filter = filter_[0] != '\0';
 		for (const Line& line : lines_)
 		{
-			if (has_filter && !icontains(line.text, filter_))
+			if (has_filter && !contains_ci(line.text, filter_))
 			{
 				continue;
 			}