feat: add keyboard navigation for select charts

[GordonSmith]

Checklist:

• The commit message is properly formatted and free of typos.
  • The commit message title makes sense in a changelog, by itself.
  • The commit message includes a "fixes" reference if appropriate.
  • The commit is signed.
• The change has been fully tested:
  • I have viewed all related gallery items
  • I have viewed all related dermatology items
• There are no similar instances of the same problem that should be addressed
  • I have addressed them here
  • I have raised new issues to address them separately

Testing:

[Copilot]

Pull Request Overview

This PR adds keyboard navigation functionality to Column and Pie chart components, enabling users to navigate and interact with chart elements using the Tab key and Space/Enter keys for selection. The changes also update repository references from "trunk" to "main" branch across multiple package.json files.

Key changes:

• Adds keyboard navigation support with Tab, Space, and Enter keys for Column and Pie charts
• Implements ARIA attributes and focus states for improved accessibility
• Updates CSS styling for hover, focus, and selection states with visual feedback
• Updates homepage URLs from "trunk" to "main" branch in package.json files

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/util/package.json	Updated homepage URL from trunk to main branch
packages/observablehq-compiler/package.json	Updated homepage URL from trunk to main branch
packages/markdown-it-plugins/package.json	Updated homepage URL from trunk to main branch (with typo)
packages/dataflow/package.json	Updated homepage URL from trunk to main branch
packages/chart/src/Pie.ts	Added keyboard navigation, ARIA attributes, and slice padding functionality to Pie chart
packages/chart/src/Pie.css	Added CSS for focus states, hover effects, and keyboard navigation styling
packages/chart/src/Column.ts	Added keyboard navigation, ARIA attributes, and Tabster integration to Column chart
packages/chart/src/Column.css	Updated CSS for selected state, added focus and hover styles
packages/chart/index.html	Added demo controls for testing keyboard navigation on both chart types

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[Copilot]

Pull request overview

Copilot reviewed 17 out of 18 changed files in this pull request and generated 24 comments.

Comments suppressed due to low confidence (2)

packages/common/src/TitleBar.ts:36

• The button element (anchor tag) should have role="button" and tabindex="0" attributes for proper accessibility. While anchor tags are naturally focusable, explicitly setting these attributes ensures correct ARIA semantics when the element behaves as a button rather than a link.

        this._i = this._element
            .attr("href", "#")
            .on("click", function () {
                context.click();
                d3Event.preventDefault();
            })
            .on("keydown", function (this: HTMLElement) {
                if (d3Event.key === " " || d3Event.key === "Spacebar" || d3Event.code === "Space") {
                    this.click();
                    d3Event.preventDefault();
                }
            })
            .on("mousemove", this.mouseMove)
            .on("mouseout", this.mouseOut)
            .append("i")
            ;

packages/graph/tests/test6.ts:75

• Unused variable g.

        const g = genData2();

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[jeclrsg]

@GordonSmith looked good. Just one nitpick about some comments and console.logs that got left behind?

Was taking a while to get through, until I remembered to tick the "hide whitespace" checkbox. I wish you could get GH to save that as a preference or something

[jeclrsg]

nitpick, a few unnecessary comments and console.logs here