feat(cloudflare-workers): add WebSocket Hibernation API support

[PAMulligan]

Summary

This PR adds support for Cloudflare's WebSocket Hibernation API in Durable Objects, addressing #4506.

New exports from hono/cloudflare-workers:

• createWSContext(ws) - Wraps a raw Cloudflare WebSocket into Hono's WSContext for use in Hibernation API handlers (webSocketMessage, webSocketClose, webSocketError)

• upgradeWebSocketForDO(ctx, options?) - Handles WebSocket upgrade using ctx.acceptWebSocket() instead of server.accept(), with optional tag support for getWebSockets(tag)

Why this matters

The Hibernation API enables long-lived WebSocket connections in Durable Objects without incurring billing charges when connections are dormant; significant cost savings for apps with idle connections.

Example usage

import { Hono } from 'hono'
import { createWSContext, upgradeWebSocketForDO } from 'hono/cloudflare-workers'

export class ChatRoom extends DurableObject {
  app = new Hono()

  constructor(ctx: DurableObjectState, env: Env) {
    super(ctx, env)
    this.app.get('/ws', (c) => upgradeWebSocketForDO(this.ctx, { tags: ['chat'] }))
  }

  fetch(request: Request) {
    return this.app.fetch(request)
  }

  webSocketMessage(ws: WebSocket, message: string | ArrayBuffer) {
    const wsCtx = createWSContext(ws)
    wsCtx.send(`Echo: ${message}`)
  }
}

Test plan

• Added unit tests for createWSContext (4 test cases)
• Added unit tests for upgradeWebSocketForDO (5 test cases)
• All existing WebSocket tests pass
• Manually tested with a Durable Object demo app

Closes #4506

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.91%. Comparing base (1aa32fb) to head (b0e8d27).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4879      +/-   ##
==========================================
+ Coverage   92.89%   92.91%   +0.01%     
==========================================
  Files         177      177              
  Lines       11797    11824      +27     
  Branches     3515     3523       +8     
==========================================
+ Hits        10959    10986      +27     
  Misses        837      837              
  Partials        1        1              

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