feat(autostart): "Start with Windows" toggle

- PM.AutoStart wraps HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
  Value "PMServer" = "<exe>" -tray. Per-user, no admin required, shows
  up in Task Manager → Startup so the user can override from there.

- UMainForm honours the -tray CLI flag (set by the registry entry):
  after the server starts, MinimizeToTray via TThread.ForceQueue so the
  app comes up directly in the tray with no visible window flash.

- Bridge cmd://autostart/{get,set} + Bridge.getAutoStart() /
  setAutoStart() / onAutoStartStatus(). Settings exposes a toggle in
  the Security section, visible only when Bridge.active (the PHP
  frontend can't touch the registry).

- Toggle reads "on" only when the registered command matches the
  current exe path, so a stale entry from a moved exe lets the user
  re-enable to refresh.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

delphi-backend/Source/PM.AutoStart.pas

@@ -0,0 +1,98 @@
+unit PM.AutoStart;
+
+{
+  Start-with-Windows toggle.
+
+  Mechanism: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
+    - Per-user (no admin needed)
+    - Visible in Task Manager → Startup tab (user can disable from there)
+    - Standard pattern used by 1Password, Bitwarden, Slack, Discord, etc.
+
+  Command line: launched with --tray so PMServer starts minimized to the
+  tray instead of popping a window during Windows login.
+
+  Value name "PMServer" — fixed string, not exe path-derived, so moving
+  the exe + flipping the toggle off/on cleans up the old entry.
+}
+
+interface
+
+function IsAutoStartEnabled: Boolean;
+
+// Returns True on success. Failures (registry locked, etc.) are silent —
+// caller surfaces the resulting status via IsAutoStartEnabled.
+function SetAutoStart(AEnabled: Boolean): Boolean;
+
+implementation
+
+uses
+  System.SysUtils, System.Win.Registry, Winapi.Windows;
+
+const
+  RUN_KEY    = 'Software\Microsoft\Windows\CurrentVersion\Run';
+  VALUE_NAME = 'PMServer';
+  TRAY_ARG   = '-tray';   // single dash so Delphi's FindCmdLineSwitch picks it up
+
+function BuildAutoStartCommand: string;
+begin
+  // Quote the exe path (may contain spaces) and append the silent-start
+  // arg. Single string written to a REG_SZ value — Windows splits args
+  // the same way CommandLineToArgvW does.
+  Result := '"' + ParamStr(0) + '" ' + TRAY_ARG;
+end;
+
+function IsAutoStartEnabled: Boolean;
+var
+  R: TRegistry;
+  LCurrent: string;
+begin
+  Result := False;
+  R := TRegistry.Create(KEY_READ);
+  try
+    R.RootKey := HKEY_CURRENT_USER;
+    if not R.OpenKeyReadOnly(RUN_KEY) then Exit;
+    try
+      if not R.ValueExists(VALUE_NAME) then Exit;
+      LCurrent := R.ReadString(VALUE_NAME);
+      // Consider the toggle "on" only if the registered command points
+      // to OUR exe — a stale entry from a moved exe should read as off
+      // so the user can re-enable to refresh the path.
+      Result := SameText(LCurrent, BuildAutoStartCommand);
+    finally
+      R.CloseKey;
+    end;
+  finally
+    R.Free;
+  end;
+end;
+
+function SetAutoStart(AEnabled: Boolean): Boolean;
+var
+  R: TRegistry;
+begin
+  Result := False;
+  R := TRegistry.Create(KEY_READ or KEY_WRITE);
+  try
+    R.RootKey := HKEY_CURRENT_USER;
+    if not R.OpenKey(RUN_KEY, True) then Exit;
+    try
+      if AEnabled then
+      begin
+        R.WriteString(VALUE_NAME, BuildAutoStartCommand);
+        Result := True;
+      end
+      else
+      begin
+        if R.ValueExists(VALUE_NAME) then
+          R.DeleteValue(VALUE_NAME);
+        Result := True;
+      end;
+    finally
+      R.CloseKey;
+    end;
+  finally
+    R.Free;
+  end;
+end;
+
+end.