Fix light mode secondary/tertiary colors rendering as white (#854)

[RomanticD]

Fixes #854.

Summary

.foregroundStyle(.secondary) (and .tertiary) rendered as pure white in light mode, making text invisible on the default white background. The root cause is an initializer-overload mismatch in Theme-DefaultImplementation.swift:

// Before
var secondary: Color {
    colorScheme == .dark ?
    Color(red: 222, green: 226, blue: 230, opacity: 0.75) :
    Color(red: 33,  green: 37,  blue: 41,  opacity: 0.75)
}

0.75 is a Double, not a Percentage, so Swift picks the Double RGB initializer that treats each channel as a 0–1 float and multiplies by 255:

public init(red: Double, green: Double, blue: Double, opacity: Double = 1) {
    let intRed   = Int(red   * 255)  // 33 * 255 = 8415
    let intGreen = Int(green * 255)  // 37 * 255 = 9435
    let intBlue  = Int(blue  * 255)  // 41 * 255 = 10455
    ...
}

The emitted CSS for --bs-secondary becomes rgb(8415 9435 10455 / 75%). Browsers clamp each channel to 255, so the color resolves to white (reported in the issue as "50 000+" channel values — same bug, seen through the devtools rounding).

Dark mode happened to look OK because white text on a dark background is still readable (it just wasn't the intended 75%-opacity light grey).

Fix

Switch the four affected call sites from Double opacities to Percentage:

// After
Color(red: 222, green: 226, blue: 230, opacity: 75%)
Color(red: 33,  green: 37,  blue: 41,  opacity: 75%)
Color(red: 222, green: 226, blue: 230, opacity: 50%)
Color(red: 33,  green: 37,  blue: 41,  opacity: 50%)

75% / 50% produce a Percentage, which is the only type that matches the integer-RGB initializer's opacity: parameter. The channels stay 33/37/41 and 222/226/230, matching the inline-comment intent (Bootstrap's standard light/dark text colors).

This touches only Theme-DefaultImplementation.swift — the default secondary and tertiary Bootstrap color variables. Custom themes that override secondary/tertiary are unaffected. No behavior change in dark mode beyond finally hitting the intended 75%/50% opacity values instead of white.

Test plan

• Added regression tests in Tests/IgniteTesting/Themes/ThemeDefaultColors.swift that assert DefaultLightTheme().secondary / DefaultDarkTheme().secondary / .tertiary resolve to the expected RGB + opacity values. The tests fail on main (e.g. color.red → 8415) and pass with this change.
• swift test — all 1124 tests pass.
• swiftlint lint — no issues on touched files.
• swift build — clean.

🤖 Generated with Claude Code

[twostraws]

Thank you!