fix(server): clean up dead socket code and fix macOS keepalive (closes #1583)

- Delete QuietHTTPServer.server_bind() override entirely:
  TCP_KEEP* setsockopts on the listening socket are no-ops without
  SO_KEEPALIVE, and SO_REUSEADDR=1 is already set by the parent class.
  The actual fix lives entirely in Handler.setup().

- Restructure Handler.setup() with per-platform branches so
  SO_KEEPALIVE=1 is always applied before timing params, and macOS
  (TCP_KEEPALIVE) gets keepalive instead of aborting on TCP_KEEPIDLE.

server.py

@@ -27,19 +27,6 @@ class QuietHTTPServer(ThreadingHTTPServer):
     daemon_threads = True
     request_queue_size = 64
     
-    def server_bind(self):
-        """Set socket options to prevent TIME_WAIT and CLOSE-WAIT accumulation."""
-        # Enable address reuse to avoid "Address already in use" errors
-        self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-        # Enable TCP keepalive to detect dead connections (Linux)
-        try:
-            self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 60)   # Start probing after 60s idle
-            self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 10)  # Probe every 10s
-            self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 3)     # Drop after 3 failed probes
-        except (OSError, AttributeError):
-            pass  # TCP_KEEP* may not be available on all platforms
-        super().server_bind()
-    
     def handle_error(self, request, client_address):
         """Override to suppress logging for common client disconnect errors."""
         exc_type, exc_value, _ = sys.exc_info()
@@ -63,19 +50,31 @@ class Handler(BaseHTTPRequestHandler):
     timeout = 30  # seconds — kills idle/incomplete connections to prevent thread exhaustion
     
     def setup(self):
-        """Set additional socket options for each connection."""
+        """Set socket options for each accepted connection."""
         super().setup()
-        # Enable TCP keepalive on the connection socket (not just server socket)
+        # TCP_NODELAY — universal, disables Nagle for HTTP latency
+        try:
+            self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        except OSError:
+            pass
+        # SO_KEEPALIVE — universal master switch (must be set before timing params)
         try:
-            import socket
-            self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)  # Disable Nagle's algorithm
-            # Aggressive keepalive: start after 10s idle, probe every 5s, drop after 3 failures
-            self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 10)
-            self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 5)
-            self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 3)
             self.connection.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
-        except (OSError, AttributeError):
-            pass  # May not be available on all platforms
+        except OSError:
+            pass
+        # Per-platform timing parameters
+        if hasattr(socket, 'TCP_KEEPIDLE'):  # Linux
+            try:
+                self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 10)
+                self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 5)
+                self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 3)
+            except OSError:
+                pass
+        elif hasattr(socket, 'TCP_KEEPALIVE'):  # macOS
+            try:
+                self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPALIVE, 10)
+            except OSError:
+                pass
     _ver_suffix = WEBUI_VERSION.removeprefix('v')
     server_version = ('HermesWebUI/' + _ver_suffix) if _ver_suffix != 'unknown' else 'HermesWebUI'
     def log_message(self, fmt, *args): pass  # suppress default Apache-style log