Release channel support - Update channel descriptions for downloads on March 4

[coreycb]

We are planning to switch the default download to the Release channel on March 4th, 2025 (136.0 release). This work will need to be timed to be published on the website the same day as the 136.0 release.

The download page at https://www.thunderbird.net/en-US/thunderbird/all/ currently has text that appears when the Daily and Release channels are selected:

• Daily channel: "The Daily version is an unstable testing and development platform, make sure you back up important data regularly!"
• Beta channel: There is no text.
• Release channel: "Thunderbird Release is available for testing purposes only until releases are deemed stable enough for official support. Make sure you backup important data regularly!"
• Extended Support Release channel: There is no text.

I propose the following text for these channels, and changing the color of the text and text box (currently pinkish red) for the stable channels (Release and ESR) to perhaps blue or another color that looks less like a warning.

• Daily channel: "The Daily channel is where development and testing begin, and new features are developed. This is expected to be the least stable channel. Make sure you back up important data regularly."
• Beta channel: "The Beta channel is where stabilization occurs. This is expected to be more stable that Daily, but not as stable as the Release or Extended Support Release channels. Make sure you back up important data regularly."
• Release channel: "The official monthly release. This release is intended for users who want all available new features and all available bug fixes on a monthly basis."
• Extended Support Release channel: "The official annual extended support release. This release is intended for users who want all available new new features on an annual basis and stability/security fixes on a monthly basis."

Can we also put "(Recommended)" next to the Release channel in the drop-down? Similar to how Firefox does. https://www.mozilla.org/en-US/firefox/all/