[written by Claude]

Second attempt at #74112, rebuilt on the approach from #74110 per review. Every lab's Run button and every when-run/setup block now share the design-system orange (--background-accent-orange-primary), and the block color is read from that CSS variable at workspace injection rather than hardcoded — so block and button have one source of truth, and both take the new brand's Primary Orange automatically at the flip.

When a student turns on a Blockly accessibility theme, the theme's setup-block color is published to redux on Blockly's own theme-change event, and the Run button follows it: High Contrast turns block and button #996300 together, and the three colorblindness themes (Protanopia, Deuteranopia, Tritanopia) turn both #FF4235. The High Contrast and colorblindness palettes themselves are untouched, and no other block colors change in any theme.

Example: open any Sprite Lab level, open workspace Settings, and switch Block Color Theme to High Contrast — the when-run block and the Run button change together, and both are still matched after a page reload. Switch back to Modern and both return to orange.

Adopted from #74110 (thanks @ebeastlake — co-authored): the theme-color sync, the redux state, the theme-change listener, and the shared Run button wiring. This PR extends that to Music Lab (its bespoke button becomes a MUI Button; its disabled state standardizes to the design-system gray), Java Lab, Python Lab/Codebridge (was purple), and Dance Party in Lab2 (Run only — Reset keeps the standard style), all through one shared style helper. Four fixes along the way:

• Sprite Lab in Lab2 no longer discards a saved accessibility theme when the display theme toggles.
• Jigsaw's theme copies block styles at load time, before the color sync runs; it now gets the synced color too.
• The blockly redux slice is registered by the publisher itself rather than assumed present: legacy labs get it from their page bootstrap, but Lab2 stores don't, which silently disabled the mirroring in Music.
• The CSS-variable read falls back on any failure: jsdom's getComputedStyle chokes on the :has() selectors MUI emits, which failed StudioApp and App Lab unit tests while real browsers were unaffected.

Verified in the browser under the new brand: Sprite Lab (High Contrast mirroring live and across reloads), Music (button conversion, play/stop toggle, High Contrast mirroring), Python Lab, Dance Party in Lab2 (Reset stays standard), jigsaw, App Lab (both phone-frame buttons, and the no-Blockly fallback path), Java Lab (including hover), and the Sprite Lab in Lab2 theme toggle.

Notes for review:

• Addresses all six review comments on Run button: new orange #74112: no purpose-named tokens, no brand-file additions, no hardcoded hex, no bespoke DOM event, and Music is a real MUI Button.
• Coordinate with [Rebrand] Option 3: Sync run button colors with when run block across Blockly themes #74110: this branch contains it; one of the two should close in favor of the other. Note the last two fixes above (the redux slice and the jsdom fallback) also apply to [Rebrand] Option 3: Sync run button colors with when run block across Blockly themes #74110 as written, so if it merges independently it should pick up both commits.
• Still stacked on Rebrand: fix music run button #74111 — inside Lab2 dark-mode containers under the new brand, the semantic orange resolves to nothing without that fix (Music's button goes invisible; a MUI Button doesn't help, since the styles still reference the CSS variable). Merge Rebrand: fix music run button #74111 first and this diff shrinks.
• For the design record: white on #F46800 is about 3.07:1 — passes WCAG for large text and non-text UI, not the 4.5:1 normal-text bar; a large improvement over the old #FFB42E at about 1.87:1. White on the High Contrast #996300 passes at 5.07:1. The hover on mirrored colors is a 12% darken (from [Rebrand] Option 3: Sync run button colors with when run block across Blockly themes #74110) rather than a design-token pair.
• Dance Party in Lab2 lives on a cached course page, which bakes the default brand at render time — it shows the new orange once the default flips and the cache re-renders.
• The adopted GameButtons test uses enzyme (kept byte-identical from [Rebrand] Option 3: Sync run button colors with when run block across Blockly themes #74110); happy to convert it to Testing Library in a follow-up if preferred.
• Expect Applitools baseline churn on lab screenshots with a Run button. Test selectors unchanged.

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