WinGet Studio: download ældre versioner

If winget is missing, WinGet Studio now offers to install it, and Settings shows the App
Installer version, with an update button where the Microsoft Store does not update it.
Per-user programs that winget refused to uninstall from an elevated app are now retried
without elevation. Every message and confirmation follows the light or dark theme. The
automatic update check at startup works again.

A new icon: a cardboard package with a command prompt stamped on its side and a download
badge, drawn for every size Windows uses so it stays sharp in the title bar, the taskbar and
Explorer. When WinGet Studio itself shows up in the Updates list, the log now points to the
Settings tab to update it.

The package is now an installer instead of a portable executable: WinGet Studio installs for
all users in Program Files, adds a Start menu entry and shows up in Windows Settings to
uninstall; preferences survive an uninstall. Upgrading from an earlier portable version
removes the portable copy and its command-line alias and installs the new one in its place.
An installed copy updates itself through the installer, verified against the published SHA-256.

Fixes only. The first list shown after launch no longer garbles accented letters in package
names and winget messages: winget writes UTF-8, and the app now reads it as UTF-8 even before
it has a console. Temporary output files left in %TEMP% by installers that keep running in
the background are removed at the next launch.

A winget failure is no longer shown as an empty list: when winget itself fails, the Updates,
Installed and Install tabs show its reason instead of "No updates available", "No installed
package found" or "No package matches", and a search where the Microsoft Store does not
answer says so.

Pins made from the app are now blocking pins, so winget refuses to upgrade the package even
when asked for it by name. Import reads package lists whose file name contains [ or ], and
refuses a list with no packages before the confirmation.

Fixes only. Installed with winget, the app no longer replaces its own executable: a
portable package is a file winget owns, and rewriting it left winget with a hash that no
longer matched, a leftover .exe.old and an uninstall entry naming the old version, so the
package could be neither upgraded nor reinstalled. Update now says to use
`winget upgrade FedeB2160.WinGetStudio`.

A tooltip on a tab no longer falls through to every control in the page, the Result column
no longer opens an empty one over rows with no result, tooltips follow the theme and wrap,
and the Updates section of Settings reads in two labelled lines instead of three stacked.

Settings and About are tabs at the right of the strip instead of a full-window overlay, so
the progress bar and the log stay visible; every tab has an icon, and the strip can show the
icon, the name or both. An update queue can be cancelled, finishing the package in flight and
stopping there, and Update locks until the next check once anything has altered the machine.
The Unknown, MS Store and Scope choices persist between launches, and the startup update check
can be turned off. The light theme has real separation between controls and page, the
scrollbars follow the theme, and a search can no longer run at the same time as a scan.

Renamed from WinGet Update Tool. Adds an Install tab with search-as-you-type, an Installed
tab with a filter and guarded uninstall, package pinning, export and import of the package
list, a settings screen, and self-update from GitHub releases.