feat(core): better next.js/cloudflare/vite support

.changeset/giant-frogs-teach.md

.github/workflows/test.yml

.nvmrc

README.md

apps/docs/blog/2024-04-26-v0.3.0.md

apps/docs/blog/img/function_tool_example.png

apps/docs/docusaurus.config.js

package.json

packages/core/e2e/examples/README.md

...ages/core/e2e/examples/cloudflare-worker-agent/.gitignore

...es/core/e2e/examples/cloudflare-worker-agent/package.json

...es/core/e2e/examples/cloudflare-worker-agent/src/index.ts

...e/e2e/examples/cloudflare-worker-agent/test/index.spec.ts

...e/e2e/examples/cloudflare-worker-agent/test/tsconfig.json

...s/core/e2e/examples/cloudflare-worker-agent/tsconfig.json

...ore/e2e/examples/cloudflare-worker-agent/vitest.config.ts

...xamples/cloudflare-worker-agent/worker-configuration.d.ts

...s/core/e2e/examples/cloudflare-worker-agent/wrangler.toml

packages/core/e2e/examples/nextjs-agent/.eslintrc.json

packages/core/e2e/examples/nextjs-agent/.gitignore