[develop] Fix: Prose-to-sample mismatches with explicit corrections

[qiutongMS]

Summary

• fix prose/code mismatches across 8 develop doc pages
• align focus session samples with the page guidance to suppress autoplay during Focus
• correct naming/property inconsistencies in tutorial and reference prose

Validation

• git diff --check
• curl -I -L https://github.com/microsoft/WindowsAppSDK-Samples/blob/main/Samples/BackgroundTask/InProc%20BackgroundTask/cs-winui/BackgroundTaskBuilder/MainWindow.xaml.cs#L79

[qiutongMS]

Review Result: APPROVED

Summary

All 8 files contain precise, technically correct fixes: property name typos, filename/extension errors, type-parameter mismatches, HTTP method corrections, and logic inversions are all resolved accurately and consistently with surrounding page content.

Must-Fix Issues

None.

Suggestions

#	File	Line/Section	Suggestion	Severity
1	focus-session.md	C++/WinRT OnFocusStateChanged	Pre-existing unused variable \�uto temp = m_focusSessionManager.IsFocusActive();\ can be removed (not introduced by this PR)	Low

Page Health Assessment

File	Overall Quality	Notes
sql-server-database.md	Good	ItemsSource fix aligns prose with correct WinUI API name
sqlite-data-access.md	Good	Spelling fix (sqlliteSample → sqliteSample) removes reader confusion
3-d-perspective-effects.md	Good	Value 0.9 matches the caption (right-hand edge) and linked screenshot
testing/index.md	Good	Class name now matches constructor UserControl1() in same snippet
listview-filtering.md	Good	Type Contact and control name FilteredListView are consistent with the XAML declaration
integrate-sharesheet-pwa.md	Good	POST description matches the manifest method:POST field
background-tasks.md	Good	File extension and casing now match the actual linked .cs file
focus-session.md	Good	Logic inversion is semantically correct — suppresses animated GIFs during focus sessions