Add React Native TV accessibility skill

[Neha]

Summary

• Add a new react-native-tv-accessibility skill for auditing React Native TV accessibility, including Vega WebView and native React Native for Vega surfaces.
• Include official-source-based references for Vega WebView, React Native for Vega, WCAG 2.2, WAI-ARIA, and TV validation.
• Add per-skill evals for trigger coverage, task scenarios, scoring, and with-skill vs without-skill comparison.

Test plan

• Verified SKILL.md frontmatter name matches the folder name.
• Checked markdown line counts and ASCII cleanliness for the new skill and evals.
• Ran Cursor lints for react-native-tv-accessibility and README.md; no linter errors found.

[knmeiss]

Ran a full eval on the skill.

Task quality (with-skill vs without-skill, 10 scenarios):

• With skill: 5/5 on all 10 scenarios, 100% assertion pass rate
• Without skill: 3.7/5 average, 70% pass rate (3 scenarios scored below passing)

The skill's value-add is Vega-platform-specific guidance. Without it, Claude handles general accessibility fine but:

• Recommends "use both aria-live and announceForAccessibility" when Vega guidance says prefer aria-live first
• Uses legacy accessibilityRole instead of Vega-recommended role prop
• Doesn't know Vega-specific detection commands (manifest.toml, @amazon-devices/webview) for identifying app type
• Misses accessibilityDescribedBy and accessibilityOrientationText for Vega RN
• Skips magnifier and VoiceView Review Mode validation steps

With the skill, all of that gets corrected. The reference files are pulling their weight.

Trigger eval (does the description activate the skill at the right time):

• Non-trigger specificity: 10/10, never fires on unrelated prompts
• Trigger precision: 7/10, misses 3 prompts it should catch

The description needs a tweak - I left an inline comment with the specific failures and a suggested revision that gets 10/10 on both.

Scope discussion: I want to chat separately about broadening this to cover React Native TV accessibility more generally (not just Vega), so we can contribute it back to the community. I'll ping you about that on slack!