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.

.gitignore

@@ -1,2 +1,33 @@
 
-vault-error.log
+vault-error.log
+
+# Delphi build artifacts
+*.dcu
+*.dcp
+*.dpu
+*.local
+*.identcache
+*.dsk
+*.~dsk
+*.~*
+*.~bpl
+*.~dll
+*.~exe
+*.exe
+*.dll
+*.bpl
+*.so
+*.dylib
+__history/
+__recovery/
+Win32/
+Win64/
+OSX64/
+Android/
+iOSDevice64/
+
+# Debug logs (created at runtime next to the exe)
+pm-debug.log
+
+# Asset build log (regenerated by BuildAssets.cmd/ps1)
+delphi-backend/assets/build.log