feat(design): strength and cardio lane colour tokens

[DX23876]

Summary

First package of the Training Load / Cardio / Strength redesign. Strength and Cardio both used effortColor, so the two training lanes could not be told apart. This adds one identity colour per lane to StrandPalette:

• strengthDeep/Color/Bright/Gradient: electric teal
• cardioDeep/Color/Bright/Gradient: violet-indigo

It covers all seven chart styles in light and dark. Signature and Health are the most vivid; Aurora and Forest are muted to fit their palettes. Orange, red and yellow are status colours and green is Charge, so a lane never reads as a status. The hex values sit in LaneColorTable, so tests read the source values directly.

No screen uses the tokens yet; the redesign packages that follow will.

Verification

• swift test --filter LaneColorTests in Packages/StrandDesign: 4/4 pass. The tests cover:
  • the strength/cardio hue distance is at least 60° per style and mode;
  • both lanes are at least 18° from statusPositive, statusWarning, statusCritical and chargeColor;
  • strengthDeep/cardioDeep against onDarkPrimary is at least 4.5:1.
• Full StrandDesign suite: 146 tests, 5 assertion failures, all inside testRecoveryStateWords (PlaceholderTests.swift, untouched here). It expects English recovery words and gets German ones under a German system locale.
• python3 Tools/doc_comment_lint.py: OK.
• The colour sheet across all styles was reviewed and approved before this PR.

Analysis migration required: no

[Copilot]

🟡 Changes recommended

Add coverage for public accessors and shared canonical palette references.

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Pull request overview

Adds style-aware Strength and Cardio identity color tokens to StrandPalette for the upcoming redesign.

Changes:

• Adds light/dark lane colors and gradients across seven chart styles.
• Adds hue-separation and contrast regression tests.
• Requires no analysis migration; tokens are not yet consumed by screens.

File summaries

File	Summary
Packages/StrandDesign/Tests/StrandDesignTests/LaneColorTests.swift	Tests lane color separation and contrast.
Packages/StrandDesign/Sources/StrandDesign/Palette.swift	Defines lane color tables and public palette accessors.

Review details

Suppressed comments (2)

Packages/StrandDesign/Sources/StrandDesign/Palette.swift:830

• The new tests never exercise the public token accessors introduced here: every assertion reads LaneColorTable.style(style) directly. A wiring error such as selecting the wrong field for an accessor or using the wrong gradient endpoints would therefore leave the suite green while consumers receive the wrong color. Add coverage that resolves each public strength*/cardio* token and both gradients for every style and scheme, or make the accessors consume a shared mapping that is itself exercised.

    public static var strengthDeep: Color {
        let hex = LaneColorTable.style(chartStyle).strengthDeep
        return Color(light: hex.light, dark: hex.dark)

Packages/StrandDesign/Tests/StrandDesignTests/LaneColorTests.swift:76

• The separation and contrast checks use copied literals for the existing status, charge, effort, and onDarkPrimary tokens rather than the canonical palette definitions. If one of those tokens changes later, these tests can still pass even though a lane becomes hue-close to the new status/charge color or its real text contrast drops below 4.5:1. Keep the reference pairs in the same source tables as their accessors, or otherwise provide one shared source of truth for production and tests.

    // Existing token hex values, copied from `StrandPalette` (Palette.swift) for the hue-separation
    // checks below — NOT changed by this change; see the file for their canonical definitions.

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite (auto)

Note

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