[Workflows] Fix docs using code review

[pombosilva]

Summary

Fixes multiple issues in Workflows documentation including missing imports, incorrect async/await usage, and code examples that wouldn't work as written.

• durable-agents.mdx: Add missing import { useState } in React WebSocket example
• bindings.mdx: Fix main entry point from .ts to .py; replace incorrect import with from workers import WorkflowEntrypoint; wrap standalone code snippets in proper WorkerEntrypoint class context with self.env instead of bare env references
• dag.mdx: Add missing await to step.sleep() call
• index.mdx: Replace non-existent await_step(step_1, step_2) with correct sequential await pattern
• python-workers-api.mdx: Add async keyword to run method signature; add missing import datetime for step.sleep_until example; add missing class imports
• limits.mdx: Fix typo "5 second" → "5 seconds" in retry delay config; remove unused variable assignment

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/docs/workflows/	@elithrar, @celso, @mia303, @jonesphillip, @cloudflare/pcx-technical-writing

[github-actions]

Preview URL: https://fc82a684.preview.developers.cloudflare.com
Preview Branch URL: https://osilva-fix-workflows-docs.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/workflows/python/bindings/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/python/bindings/
https://developers.cloudflare.com/workflows/python/python-workers-api/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/python/python-workers-api/
https://developers.cloudflare.com/workflows/python/dag/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/python/dag/
https://developers.cloudflare.com/workflows/reference/limits/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/reference/limits/
https://developers.cloudflare.com/workflows/python/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/python/
https://developers.cloudflare.com/workflows/get-started/durable-agents/	https://osilva-fix-workflows-docs.preview.developers.cloudflare.com/workflows/get-started/durable-agents/

[elithrar]

@pombosilva all PRs need a description of the changes & fixes please.