Fix Peek always showing warning message by updating IsWarningMessageVisible logic (#40056)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request
This PR fixes an issue where the warning message in Peek was always
displayed, even when not applicable.

**Root cause**
When non-video files were triggered, the logic did not call
`IsWarningMessageVisible(string? missingCodecName)`
as expected. As a result, the default UI state caused the warning
message to always appear.

**Fix**
Updated the method signature and call sites to:
`public Visibility IsWarningMessageVisible(IPreviewer? previewer,
PreviewState? state)`
This ensures that the logic is consistently triggered across different
preview handlers and has access to the necessary context to determine
whether the warning message should be shown.

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [ ] **Closes:** #xxx
- [ ] **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

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml

@@ -65,7 +65,7 @@
             HorizontalAlignment="Center"
             VerticalAlignment="Center"
             Foreground="{StaticResource TextFillColorSecondaryBrush}"
-            Visibility="{x:Bind IsWarningMessageVisible(VideoPreviewer.MissingCodecName), Mode=OneWay}">
+            Visibility="{x:Bind IsWarningMessageVisible(VideoPreviewer, Previewer.State), Mode=OneWay}">
             <Paragraph>
                 <Run Text="{x:Bind GetWarningMessage(VideoPreviewer.MissingCodecName), Mode=OneWay}" />
                 <Hyperlink Click="CodecSearchHyperlink_Click">

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml.cs

@@ -150,9 +150,9 @@ namespace Peek.FilePreviewer
             return isValidPreview ? Visibility.Visible : Visibility.Collapsed;
         }
 
-        public Visibility IsWarningMessageVisible(string? missingCodecName)
+        public Visibility IsWarningMessageVisible(IPreviewer? previewer, PreviewState? state)
         {
-            var shouldShow = !string.IsNullOrEmpty(missingCodecName);
+            var shouldShow = previewer is IVideoPreviewer videoPreviewer && MatchPreviewState(state, PreviewState.Loaded) && !string.IsNullOrEmpty(videoPreviewer.MissingCodecName);
 
             return shouldShow ? Visibility.Visible : Visibility.Collapsed;
         }