fix(changelog): restore heading position and normalize bullets

[TGPSKI]

Problem

file_prepend inserted the v0.2.1 changelog section above the
# Changelog heading, breaking the rendered document structure on GitHub.
Bullet points were also rendered as • instead of -.

Fix

• Moves the # Changelog heading back to line 1
• Reorders content so new version sections appear after the heading
• Replaces • bullet characters with - throughout the affected section

Validation

• # Changelog is the first line of the file
• Version sections appear in descending order below the heading
• All bullets use - not •