[Improve] Make routine Discord release announcements more compact

[roomote-roomote]

Created by Roomote. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

• Parse release notes into their introduction and named sections before formatting.
• Assemble compact patch/minor and detailed major announcements through separate message builders.
• Keep detailed highlights for major releases while removing the redundant changelog heading and extra intro spacing.
• Add the arrow treatment to release-note links while continuing to suppress Discord link embeds.

Why this change was made

Routine releases should draw less attention in Discord, while major releases can still use the fuller announcement format.

Impact

Patch and minor announcements are shorter and quieter. Major announcements remain detailed but no longer repeat the version/date heading or add unnecessary whitespace before highlights.

[roomote-community]

No new code issues found. See task

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