Clean up common/ comments and the log-ring strncpy warning

Comments must not document the past or reference plan circumstances:
drop the stale pointer to a never-created audio_correlate_layout.hpp,
the "step b" plan labels, the "carved out of reserved space" history
note, and a README pointer; reword a past-tense seqlock comment to
describe the failure mode in the present.

Replace the strncpy in log_ring_push with a bounded memcpy: same
semantics (truncate + NUL), but without the C4996 deprecation warning
on every host build.

common/include/coop/audio_correlate.hpp

@@ -15,8 +15,8 @@
 //
 // This header is the pure, headless-testable core (no devices, no WASAPI). The host downmixes the
 // two captures to mono float, calls correlate_rate(), and feeds the result into the existing rate
-// path (publish / override). audio_correlate_layout.hpp (step b) reuses these helpers to also
-// recover channels + bit depth by trying candidate de-interleavings.
+// path (publish / override). correlate_format() below builds on the same helpers to also recover
+// channels + bit depth by trying candidate de-interleavings.
 #pragma once
 
 #include <cmath>
@@ -254,7 +254,7 @@ inline RateCorrelation correlate_rate(const std::vector<float>& hook_mono, const
 	return result;
 }
 
-// --- Step (b): channels + bit-depth recovery --------------------------------------------------
+// --- Channels + bit-depth recovery -------------------------------------------------------------
 //
 // The rate step assumes the hook bytes are de-interleaved at the device channel/bit layout. When a
 // game renders a DIFFERENT layout than the device (e.g. stereo float on a 7.1 endpoint, or 16-bit