Release 0.9.10 refresh fixes

[ehud-am]

Summary

• fix Markdown refresh flicker by avoiding active-file refetches when only other paths changed
• keep local Markdown image sources visible across rerenders while refreshing in the background
• fix parent-folder navigation so cached empty directory data cannot make a non-empty folder appear empty
• bump to 0.9.10 and update audited build dependencies/cask metadata

Validation

• npm run verify
• packaging/macos/release/package-app.sh
• packaging/macos/release/test-package.sh
• packaging/macos/release/validate-artifact.sh packaging/macos/release/artifacts/GitLocal-0.9.10-macos.zip
• packaging/macos/release/validate-version-alignment.sh
• packaging/macos/cask/validate-cask.sh packaging/macos/cask/gitlocal.rb
• packaging/macos/cask/test-install-cask.sh packaging/macos/cask/gitlocal.rb packaging/macos/release/artifacts/GitLocal-0.9.10-macos.zip
• npm pack --dry-run