feat: Delphi backend + JS↔Delphi bridge (clipboard, tray, auto-lock)

Introduces the Delphi 12 FMX backend (PMServer) that hosts the embedded
WebView2 vault on 127.0.0.1, and a native bridge between JS and Delphi
that wires three privacy-focused features:

1. Secure clipboard
   Copying a password registers the Win32 "ExcludeClipboardContentFromMonitorProcessing"
   format alongside CF_UNICODETEXT, so Win+V clipboard history never sees
   the value. Auto-clears after 30s via TTimer. Bridge.copySecure() in
   app.js routes all password/username/secret copy paths through the
   native layer when running inside the Delphi WebView2 (falls back to
   navigator.clipboard for the PHP standalone).

2. Tray icon (X-to-tray when server running)
   Closing the dev panel hides both the form HWND and the TFMAppClass
   per-process proxy window that owns the FMX taskbar entry — the form's
   HWND alone is not the taskbar-visible one in FMX (took some iteration
   to discover). Tray menu: Open, Lock vault, Quit. Clipboard is force-
   cleared on minimize as extra safety. First-time minimize fires a
   balloon notification so the user knows the app is still running.

3. Auto-lock on Windows session lock (Win+L)
   wtsapi32.dll!WTSRegisterSessionNotification on a dedicated message-only
   window. On WM_WTSSESSION_CHANGE / WTS_SESSION_LOCK, the bridge calls
   ExecuteJavaScript('lockVault()'). Same path used by the tray "Lock vault"
   menu item.

Bridge architecture:
 - JS → Delphi via cmd:// URLs intercepted in OnBeforeNavigate
   (pattern lifted from DeskInsight Monaco). Currently exposes
   cmd://clipboard/copy?text=...&clear=... and cmd://clipboard/clear.
 - Delphi → JS via TTMSFNCWebBrowser.ExecuteJavaScript with guarded
   calls (typeof check) so the bridge degrades cleanly if app.js isn't
   loaded yet.

Files:
 - Source/PM.Bridge.pas (new) — TSecureClipboard + TPMBridge
 - UMainForm.pas/.fmx — bridge wiring, FormCloseQuery intercept, tray
   callbacks (BridgeTrayRestore / BridgeLockRequest / BridgeQuit)
 - js/app.js — Bridge object, 5 navigator.clipboard sites migrated to
   Bridge.copySecure with PHP-compatible fallback, Bridge.onTrayRestore
   handler that resets the auto-lock timer

.gitignore extended with Delphi build artifacts (*.dcu, Win32/, Win64/,
__history/, __recovery/, *.identcache, *.dsk, *.local, etc.) so source
checkouts stay clean.

delphi-backend/Source/PM.JSON.pas

@@ -0,0 +1,78 @@
+unit PM.JSON;
+
+interface
+
+uses
+  System.SysUtils, System.Classes, System.JSON, IdCustomHTTPServer;
+
+type
+  TJSONHelper = class
+  public
+    class function ReadBody(ARequest: TIdHTTPRequestInfo): TJSONObject;
+    class procedure SendJSON(AResponse: TIdHTTPResponseInfo; AObj: TJSONValue;
+      ACode: Integer = 200; AOwnsObj: Boolean = True);
+    class procedure SendError(AResponse: TIdHTTPResponseInfo; ACode: Integer;
+      const AMsg: string);
+    class procedure SendOK(AResponse: TIdHTTPResponseInfo; const AMessage: string = 'OK');
+  end;
+
+implementation
+
+class function TJSONHelper.ReadBody(ARequest: TIdHTTPRequestInfo): TJSONObject;
+var
+  S: string;
+  LSS: TStringStream;
+  LValue: TJSONValue;
+begin
+  Result := nil;
+  if ARequest.PostStream = nil then Exit(TJSONObject.Create);
+  LSS := TStringStream.Create('', TEncoding.UTF8);
+  try
+    ARequest.PostStream.Position := 0;
+    LSS.CopyFrom(ARequest.PostStream);
+    S := LSS.DataString;
+  finally
+    LSS.Free;
+  end;
+  if Trim(S) = '' then Exit(TJSONObject.Create);
+  LValue := TJSONObject.ParseJSONValue(S);
+  if LValue is TJSONObject then
+    Result := TJSONObject(LValue)
+  else
+  begin
+    LValue.Free;
+    Result := TJSONObject.Create;
+  end;
+end;
+
+class procedure TJSONHelper.SendJSON(AResponse: TIdHTTPResponseInfo;
+  AObj: TJSONValue; ACode: Integer; AOwnsObj: Boolean);
+begin
+  AResponse.ResponseNo := ACode;
+  AResponse.ContentType := 'application/json; charset=utf-8';
+  AResponse.CharSet := 'utf-8';
+  AResponse.ContentText := AObj.ToJSON;
+  if AOwnsObj then AObj.Free;
+end;
+
+class procedure TJSONHelper.SendError(AResponse: TIdHTTPResponseInfo;
+  ACode: Integer; const AMsg: string);
+var
+  LObj: TJSONObject;
+begin
+  LObj := TJSONObject.Create;
+  LObj.AddPair('error', AMsg);
+  SendJSON(AResponse, LObj, ACode);
+end;
+
+class procedure TJSONHelper.SendOK(AResponse: TIdHTTPResponseInfo;
+  const AMessage: string);
+var
+  LObj: TJSONObject;
+begin
+  LObj := TJSONObject.Create;
+  LObj.AddPair('message', AMessage);
+  SendJSON(AResponse, LObj);
+end;
+
+end.