UptimeRobot: colorize percentage to work with both dark and light bg

[huyz]

The problem is that right now UptimeRobot shows uptime percentages in gray, which actually show up as black
when I have a dark background, making it tough to read.

I figured we might as well color-code the percentages, just as it's done for the Charge field
of the Power module, which makes the text readable on light and dark background.

[Copilot]

Pull request overview

This PR updates the UptimeRobot widget so uptime percentages are colorized instead of rendered in gray, aligning that display with the codebase’s other percentage-based widgets and improving readability on different backgrounds.

Changes:

• Added a dedicated ColorizeUptimePercent helper with uptime-specific thresholds.
• Updated the UptimeRobot widget to render uptime values with inline colors.
• Refactored uptime string formatting to split, parse, and rebuild each uptime segment before display.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
utils/colors.go	Adds a new utility for colorizing uptime percentages with stricter thresholds near 100%.
modules/uptimerobot/widget.go	Switches UptimeRobot uptime rendering from gray text to per-value colored output and rewrites uptime formatting.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.