Downloads section in release notes need improvement

[ErikBjare]

See title.

Should also include AppImage's, should also maybe mention package managers which should support/get the version (not really applicable for pre-releases etc?).

Should also list/include the tauri as alternate distribution? (must not confuse users - but worth noting that Tauri dist supports Wayland)

Also see https://activitywatch.net/downloads/, which is also lacking mentions of the tauri distribution.

[ErikBjare]

@TimeToBuildBob Get on it

[ErikBjare]

See for e.g. https://github.com/ActivityWatch/activitywatch/releases/tag/v0.14.0b7

[TimeToBuildBob]

Opened #1454: expands the release-notes Downloads section (scripts/build_changelog.py) with .deb/AppImage links for Linux, an Apple Silicon .dmg link for macOS, and a note pointing at the Tauri-based alternate build (calling out Wayland support on Linux).

Left out of scope for now:

• Exact per-asset Tauri links — current release asset naming is inconsistent across platforms (some use a v prefix on the version, some don't), so I used a prose pointer to the activitywatch-tauri-* assets instead of hardcoded links that could 404 on the next release.
• Package managers — didn't find any package-manager distribution wired up yet to link to.
• https://activitywatch.net/downloads/ — couldn't find the source repo for that page from this checkout, so the Tauri mention there is still missing. Let me know which repo that is and I'll follow up.

[TimeToBuildBob]

Opened #1455.

Changes:

• macOS arm64 (Apple Silicon) link alongside Intel
• Linux AppImage and .deb alongside zip
• Tauri section labelled "experimental" with Wayland note
• Handled Tauri AppImage version naming (no v prefix)