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/Handlers/PM.Handler.Passkey.pas

@@ -0,0 +1,47 @@
+unit PM.Handler.Passkey;
+
+(*
+  WebAuthn / Passkey endpoints — stubbed to 501 Not Implemented.
+
+  Why stubbed: full WebAuthn server requires:
+    - CBOR decoder for COSE keys + attestation objects
+    - DER ASN.1 encoder for ES256/RS256 public keys
+    - ECDSA P-256 signature verification (no native Delphi support)
+    - Challenge management with constant-time compares
+  Roughly 500-700 lines of crypto-sensitive code. The PHP version (api.php
+  lines 168-657) handles this with OpenSSL bindings. A faithful Delphi port
+  would either bind libssl/libcrypto DLLs or pull in a pure-Pascal EC lib.
+
+  For v1 of the Delphi backend we return 501 with a clear message so the
+  frontend gracefully falls back to master password login. The PHP backend
+  remains the reference for passkey-enabled deployments.
+
+  When implemented, see:
+    api.php :169-211   cbor_decode, derLen, coseToPem
+    api.php :537-657   register/begin, register/complete, login/begin, login/complete
+*)
+
+interface
+
+implementation
+
+uses
+  System.SysUtils,
+  IdCustomHTTPServer,
+  PM.Router, PM.JSON;
+
+procedure HandleStub(ARequest: TIdHTTPRequestInfo;
+  AResponse: TIdHTTPResponseInfo; const AParams: TArray<string>);
+begin
+  TJSONHelper.SendError(AResponse, 501,
+    'Passkey/WebAuthn is not implemented in the Delphi backend yet. ' +
+    'Use master-password login, or run the PHP backend for passkey support.');
+end;
+
+initialization
+  Router.Register('POST', '/passkey/register/begin',    HandleStub);
+  Router.Register('POST', '/passkey/register/complete', HandleStub);
+  Router.Register('POST', '/passkey/login/begin',       HandleStub);
+  Router.Register('POST', '/passkey/login/complete',    HandleStub);
+
+end.