chore(release): prepare v3.9.3

[ThisIs-Developer]

Summary

Prepares Markdown Viewer v3.9.3 after the completed Explorer, toolbar, responsive UI, and localization redesign was merged in #222.

Changes

• updates the browser application version to 3.9.3
• updates Neutralino and desktop package metadata to 3.9.3
• synchronizes the bundled desktop application script
• advances the service-worker cache key for clean client upgrades
• adds the complete v3.9.3 changelog entry

Release validation

• generated all seven standalone Neutralino desktop binaries locally
• verified release-version consistency across tracked version sources
• git diff --check passed
• the local-only static smoke script remains incompatible with the intentionally restored root file layout because it references ignored assets/js/app.js paths; it is not tracked or part of the release source

Release impact

Once merged, tag v3.9.3 will trigger the desktop release workflow, publish Linux, macOS, and Windows binaries, and generate SHA256SUMS.txt.

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Project	Deployment	Actions	Updated (UTC)
markdown-viwer	Ready	Preview, Comment	Jul 19, 2026 9:56pm