[Fix] possible fix to Heroic does not stay minimized #5611

[MateoGonzalezLourido]

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What

Fixes the "minimize on launch" feature not maintaining the hidden state on
subsequent game launches without reopening Heroic.

related to #5611

Root cause

launchEventCallback called mainWindow.hide() unconditionally whenever
minimizeOnLaunch && !noTrayIcon, with no check for whether the window was
already hidden.

After the first game exits, the window stays hidden (there is no show() call
in the exit path). On the second launch — e.g. from the tray icon's
"Recent Games" context menu, without explicitly reopening Heroic — hide() was
called on an already-hidden window ( this causes the
window to briefly flash with a frozen/blank background before the game starts and leaves the window state inconsistent for subsequent launches.).

protocol.ts already guards against this with an isVisible() check
(lines 128-134); launchEventCallback was missing the same guard.

Changes

src/backend/launcher.ts

• Added mainWindow?.isVisible() guard before calling hide(), consistent
  with the pattern already used in protocol.ts. This prevents calling hide()
  on an already-hidden window, which caused the blank-window flash and
  inconsistent state on Linux.

• Fixed powerDisplayId never being reset to null after
  powerSaveBlocker.stop(). Because of this, starting from the third game
  launch the guard if (!powerDisplayId) evaluated to false (non-zero integer
  is truthy), silently skipping the display-sleep blocker for all subsequent
  sessions.

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I can't test it.It works just as well on my PC as the original.

Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)