feat(dashboards): table conditional formatting

[TanayBensuYurtturk]

Summary

Adds table conditional formatting: a per-column format (string shorthand or object) that combines number display with value-based coloring. Supports flat fills, gradients with domain anchors (value / percent / percentile), built-in schemes and dashboard-level custom palettes, rule-based styling (all operators, cross-column comparisons, text styles), and like to mirror another column. Works in both YAML and TSX, is validated by dac validate, and named colors adapt to light/dark mode.

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
frontend/src/components/widgets/TableWidget.tsx:65-66
**Chained `like` resolves wrong source**

When column A uses `like: B` and B uses `like: C`, A adopts B's unresolved format but uses B's data index while B uses C's values, causing A to render different colors from the column it is configured to mirror.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "feat(dashboards): add table conditional ..." | Re-trigger Greptile}

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_{Reviews (2): Last reviewed commit: "fix(dashboards): resolve chained format...." | Re-trigger Greptile}

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_{Reviews (3): Last reviewed commit: "revert(dashboards): drop custom palettes..." | Re-trigger Greptile}

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
frontend/src/components/widgets/TableWidget.tsx:60-64
**Cyclic `like` resolves wrong source**

When configured columns form a multi-column cycle such as A → B → A, validation accepts it and this traversal returns the revisited A as a terminal source, causing cells to silently use the wrong format and value source.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (4): Last reviewed commit: "polish(dashboards): softer table fills a..." | Re-trigger Greptile}

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_{Reviews (5): Last reviewed commit: "fix(dashboards): bail out of cyclic form..." | Re-trigger Greptile}

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_{Reviews (6): Last reviewed commit: "polish(dashboards): let cell text follow..." | Re-trigger Greptile}

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_{Reviews (13): Last reviewed commit: "docs(dashboards): trim conditional-forma..." | Re-trigger Greptile}