fix: correct .d.ts path and update deps

[isamu]

Summary

• Changed from "./core" to from "./core/index" in src/index.ts to fix .d.ts resolution
• Updated devDependencies to latest versions (eslint 10, vite 8, tailwindcss 4.2, gui-chat-protocol 0.0.4, etc.)
• Bumped version to 0.2.2

Test plan

• yarn build succeeds
• yarn lint passes

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