fix(windows): make the "Open with" registration an optional installer task #1595

Problem

The Inno Setup installer always writes the HKCR\Applications\querya_desktop.exe keys (friendly name, icon, open command, SupportedTypes for .sql / .sqlite / .sqlite3 / .db / .db3), so Querya shows up in the Windows "Open with" menu for those files whether or not the user asked for it. The .sql and SQLite associations are already separate, unchecked tasks; this registration is not.

Fix

• New unchecked task openwith in packaging/windows/querya.iss, in the "File associations" group.
• All Applications\{#MyAppExeName} registry entries get Tasks: openwith.

Notes

• Existing installs keep the keys until uninstall (Inno removes uninsdeletekey keys only then).
• Not verified locally: compile with ISCC in CI or on a Windows machine.