Phase 5 (D4): headless daemon entry point (ewsdrd)

ewsdrd.lpr — a console daemon that runs TRadioController + TWebAdapter WITHOUT
TMainForm/LCL, proving the Phase-5 goal: web-only headless operation. THeadlessHost
wires the data-path callbacks to the controller, the web command handlers to the
adapter (lifecycle ones marshalled to the main thread via FCtrl.Invoke =
TThread.Synchronize), opens WDSP synchronously, autostarts the saved device, and
runs a CheckSynchronize + periodic PushState loop. SIGINT/SIGTERM → graceful
StopAndDisconnect (persist + Run=0).

To keep the controller graph truly LCL-free, PlatformUtils now guards its only
Forms dependency (Screen.PixelsPerInch in CurrentScreenDPI) behind {$IFNDEF
HEADLESS}; the GUI build is byte-identical (HEADLESS undefined). build-ewsdrd.sh
compiles the headless graph from source with -Mobjfpc (nested comments) -dHEADLESS
into a separate lib-headless/ output dir, untouching the GUI .ppu.

Verified: builds clean; runs headless, web server up (HTTP 401 = serving), no LCL;
SIGINT shuts down gracefully. Radio-connect + web round-trip need hardware to test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

PlatformUtils.pas

@@ -22,7 +22,7 @@ function GetAppCfgDir: string;
 implementation
 
 uses
-  SysUtils, Forms;
+  SysUtils {$IFNDEF HEADLESS}, Forms{$ENDIF};
 
 function QtPlatformAllowsOpenGLControls: Boolean;
 var
@@ -62,8 +62,12 @@ end;
 
 function CurrentScreenDPI: Integer;
 begin
+{$IFNDEF HEADLESS}
   Result := Screen.PixelsPerInch;
   if Result <= 0 then Result := 96;
+{$ELSE}
+  Result := 96;   // headless-демон без LCL: экрана нет, дефолт DPI
+{$ENDIF}
 end;
 
 function GetAppCfgDir: string;