fix(startup): use ApplicationHWND + WS_EX_TOOLWINDOW, restore it on show

Adopts the approach that actually works: ApplicationHWND (FMX.Platform.Win) IS
the taskbar proxy, so there is nothing to hunt for and it is valid before the
form exists. And hiding it was never enough — the taskbar had already drawn
the button; clearing WS_EX_APPWINDOW and setting WS_EX_TOOLWINDOW is what
removes it, since a tool window is never listed.

That style is permanent, which is why the button never came back after a
restore. TrayProxyShowInTaskbar puts it back, called from
RestoreWindowFromTray — the single choke point every tray restore already goes
through — so it lands before RestoreFromTray shows the windows and the style
takes effect on that show.

Removes the scaffolding this chase accumulated and that the real fix makes
pointless: the EVENT_OBJECT_SHOW hook, the polling worker, FindOurFMXAppWindow,
TrayHideNow with its four probes, the one-shot OnActivate hide, and the [tray]
tracing. ~4.8 KB of dead code.

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

delphi-backend/PMServer.dproj

@@ -204,6 +204,7 @@ $(PreBuildEvent)]]></PreBuildEvent>
         <Icon_MainIcon>PMServer_Icon1.ico</Icon_MainIcon>
         <UWP_DelphiLogo44>app.png</UWP_DelphiLogo44>
         <UWP_DelphiLogo150>app.png</UWP_DelphiLogo150>
+        <Debugger_RunParams>-tray</Debugger_RunParams>
     </PropertyGroup>
     <ItemGroup>
         <DelphiCompile Include="$(MainSource)">