Addressing post-publish issues.

[gspencergoog]

Description

This fixes some issues discovered after publishing.

• Home page URLs were invalid
• Some versions of some packages weren't compatible with the minimum allowed versions of other packages (needed downgrade testing).
• flutter_markdown has been discontinued (replaced with flutter_markdown_plus.

[gemini-code-assist]

Code Review

This pull request addresses several important maintenance tasks. The fixes for invalid homepage URLs, the dependency updates to ensure compatibility, and the migration from the discontinued flutter_markdown package to flutter_markdown_plus are all well-implemented. While the PR title 'Adding file lost in merge' is a bit confusing as no files were added, the changes themselves are clear and beneficial for the repository's health. The updates across the various pubspec.yaml files and the corresponding code changes are correct. Given that these changes fix issues in published packages, I recommend incrementing their patch versions (e.g., 0.5.0 to 0.5.1) before the next release to ensure consumers receive these important fixes.