Release Flet version 0.80.5

[FeodorFitsner]

Bump Flet package version to 0.80.5 and update changelogs with new features and fixes, including memory leak fix for web apps, LaTeX support in Markdown, improved app routing, and PyInstaller icon data inclusion. Added release preparation skill documentation.

Summary by Sourcery

Prepare the 0.80.5 Flet release with updated versioning, changelogs, and internal release documentation.

New Features:

• Document LaTeX support in Markdown and improved app routing behavior in the changelogs.

Bug Fixes:

• Document the memory leak fix for Flet web apps in the changelogs.
• Document inclusion of material and cupertino icon data for PyInstaller builds in the changelogs.

Documentation:

• Add an internal release preparation skill document describing the steps to create a new Flet release.

[sourcery-ai]

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