chore: use ESM package configuration in all examples

[chenjiahan]

This PR standardizes every example package on ESM by adding "type": "module" and renaming .mjs / .mts files to .js / .ts.

For Rspack examples, source imports remain extensionless and fullySpecified resolution is disabled with module rules. It also updates CommonJS-only scripts and Node output extensions so the examples continue to build and run under ESM package scopes.

Verification

• pnpm build:rspack
• pnpm test
• pnpm exec rslint
• Prettier check for all changed files

[chatgpt-codex-connector]

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