feat: add device diagnostics for missing voice replies

Track microphone levels, short reads and PCM buffer drops. Report audio
queue admission separately from TLS writes, expose server replies and
ACKs before filtering, and capture per-round counters before timeouts.

Add diagnostic regression coverage and support POSIX hosts in WSS tests.

tools/test_wss_receive.py

@@ -1,6 +1,7 @@
 """Exercise the real receive/upgrade loop with delayed TLS records."""
 from pathlib import Path
 import subprocess
+import os
 
 root = Path(__file__).resolve().parents[1]
 lib = root / 'ql-application/threadx/interface/custom_app/lib/librws'
@@ -37,6 +38,7 @@ typedef struct {
     char *payload_buff, *received;
     size_t received_size, received_len;
     int socket, command, is_connected;
+    unsigned int diag_rx_calls, diag_rx_bytes;
     const char *error;
 } _rws_socket;
 static int replies[16], reply_count, calls, closes;
@@ -120,7 +122,10 @@ output.mkdir(parents=True, exist_ok=True)
 cfile = output / 'test_wss_receive.c'
 cfile.write_text(harness, encoding='utf-8')
 exe = output / 'test_wss_receive.exe'
-subprocess.run(['cl', '/nologo', '/W4', '/WX', '/wd4018', '/TC',
-                '/I' + str(lib / 'inc'), str(cfile), str(lib / 'src/rws_handshake.c'),
-                '/Fo' + str(output) + '/', '/Fe' + str(exe)], check=True)
+if os.name == "nt":
+    subprocess.run(['cl', '/nologo', '/W4', '/WX', '/wd4018', '/TC',
+                    '/I' + str(lib / 'inc'), str(cfile), str(lib / 'src/rws_handshake.c'),
+                    '/Fo' + str(output) + '/', '/Fe' + str(exe)], check=True)
+else:
+    subprocess.run(['cc', '-std=c99', '-Wall', '-Wextra', '-Werror', '-Wno-sign-compare', '-I' + str(lib / 'inc'), str(cfile), str(lib / 'src/rws_handshake.c'), '-o', str(exe)], check=True)
 subprocess.run([str(exe)], check=True)