Release Panelize 1.2.8

[Manho]

Summary

• Bump Panelize from 1.2.7 to 1.2.8.
• Add the 1.2.8 changelog entry for the localized Gemini Send All fix.
• Refresh release metadata for the Chrome Web Store and GitHub Release packages.

Included fix

• Fix Gemini Send All behavior in localized interfaces #63 fixes Gemini Send All in localized interfaces without changing the image-upload path.
• Related issue: all AI can send "Enter" key except Gemini. #53.

Validation

• Release Prep: https://github.com/Manho/Panelize/actions/runs/29673444195
• Release PR gate passed locally.
• Unit tests: 36 files and 304 tests passed.
• Both generated ZIPs contain manifest version 1.2.8 and SHA-256 4afe01e2310c129b08d7478c5f9b0902590ca6f61f6c900e3294007f88af633c.