Add Charts2 Storybook samples

[xrendan]

Summary

• add the Charts2 package and include its stories in the root Storybook config
• add CLI-ready sample chart definitions for the supported chart families
• render the actual embedded Build Canada square / Canada Spends SVG logos in top-right chart chrome
• size the logo to the rendered height of the title plus subtitle block
• keep chart title and subtitle rendering in Söhne Kräftig, with SVG markup coverage
• add descending x-axis tick marks, dashed y-axis spacing gridlines, dashed vertical value markers without duplicate bottom stubs, and production-style Grapher palettes
• add sample, axis, chrome, theme, SceneSVG, and corpus coverage for these visual defaults

Verification

• bun test src/core/layout/axis.test.ts
• bun test src/core/layout/axis.test.ts src/core/layout/chrome.test.ts src/react/SceneSVG.test.tsx src/core/theme/themes.test.ts src/samples.test.ts
• bun test src/corpus/corpus.test.ts
• bun run typecheck
• bun src/cli/index.ts render samples/line-provincial-budgets.json --out -

Note: earlier, bun test src/cli/render.test.ts was run; the existing PNG rasterization smoke test timed out after 5s, while the rest of that file passed.