fix: Improve tray icon theming and installer icon handling (#44715)

Add "svgs" directory and icon files to installer, ensuring proper
install/uninstall and registry registration. Enhance logging in
general_settings.cpp for theme-adaptive tray icon config changes.
Refactor tray_icon.cpp to improve icon loading robustness, add detailed
diagnostics, and ensure fallback to default icon if theme-adaptive icon
fails to load. These changes improve error handling and maintainability
for tray icon theming.

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request

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## PR Checklist

- [ ] Closes: #xxx
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- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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Co-authored-by: Yu Leng <yuleng@microsoft.com>

installer/PowerToysSetupVNext/Core.wxs

@@ -61,6 +61,16 @@
         </RegistryKey>
         <File Source="$(var.RepoDir)\Notice.md" Id="Notice.md" />
       </Component>
+      <Directory Id="SvgsFolder" Name="svgs">
+        <Component Id="svgs_icons" Guid="A9B7C5D3-E1F2-4A6B-8C9D-0E1F2A3B4C5D" Bitness="always64">
+          <RegistryKey Root="$(var.RegistryScope)" Key="Software\Classes\powertoys\components">
+            <RegistryValue Type="string" Name="svgs_icons" Value="" KeyPath="yes" />
+          </RegistryKey>
+          <File Id="icon.ico" Source="$(var.BinDir)svgs\icon.ico" />
+          <File Id="PowerToysWhite.ico" Source="$(var.BinDir)svgs\PowerToysWhite.ico" />
+          <File Id="PowerToysDark.ico" Source="$(var.BinDir)svgs\PowerToysDark.ico" />
+        </Component>
+      </Directory>
     </DirectoryRef>
 
     <?if $(var.PerUser) = "true" ?>
@@ -112,6 +122,7 @@
         <RemoveFolder Id="RemoveBaseApplicationsAssetsFolder" Directory="BaseApplicationsAssetsFolder" On="uninstall" />
         <RemoveFolder Id="RemoveWinUI3AppsInstallFolder" Directory="WinUI3AppsInstallFolder" On="uninstall" />
         <RemoveFolder Id="RemoveWinUI3AppsAssetsFolder" Directory="WinUI3AppsAssetsFolder" On="uninstall" />
+        <RemoveFolder Id="RemoveSvgsFolder" Directory="SvgsFolder" On="uninstall" />
         <RemoveFolder Id="RemoveINSTALLFOLDER" Directory="INSTALLFOLDER" On="uninstall" />
       </Component>
       <ComponentRef Id="powertoys_exe" />
@@ -120,6 +131,7 @@
       <ComponentRef Id="powertoys_toast_clsid" />
       <ComponentRef Id="License_rtf" />
       <ComponentRef Id="Notice_md" />
+      <ComponentRef Id="svgs_icons" />
       <ComponentRef Id="DesktopShortcut" />
       <?if $(var.PerUser) = "true" ?>
       <ComponentRef Id="powertoys_env_path_user" />