Update website changelog

[Hans5958]

This PR updates the website changelog, including the changes from after the latest changelog on February, to the date this PR is made. It is based on

• commits made after 8 February 2025 (commits after VocaDB/vocadb@77ac1fa)
• website update maintenance annoucements made on the Discord channel (for release date sync)
• some general observation and notes from the activity of the site and the Discord server.

Notes

• Some dates doesn't have an appropriate website update maintenance announcement on the Discord channel. Please check whether the dates are accurate.
• Some changes may not be reflected on the commits (such as the force change of TetoDB on April Fools 2025, which I'd assume it is the case on 2024 but not mentioned on the changelog, hence not added on the changelog, and the recent Band/unit artist type addition).
• Generative AI is used for ensure linguistic similarity to the previous changelog entries.

TODO (for staff)

• Check whether the written changelog is accurate
• Check whether that all notable changes have been mentioned