feat(cloudflare): add Rate Limit binding

[Dawsson]

Issue

Alchemy v2 could not model a Cloudflare Workers Rate Limiting binding. Cloudflare configures this through Worker metadata as a ratelimit binding with namespace_id and a simple limit window. The runtime binding exposes limit({ key }).

Docs:

• https://developers.cloudflare.com/workers/runtime-apis/bindings/rate-limit/

Solution

• Add Cloudflare.RateLimit as a pure Worker binding marker.
• Emit { type: "ratelimit", name, namespaceId, simple } in Worker metadata.
• Include Rate Limit in Cloudflare.InferEnv as RateLimit.

Validation

• node_modules/.bin/oxfmt packages/alchemy/src/Cloudflare/RateLimit/RateLimit.ts packages/alchemy/src/Cloudflare/RateLimit/index.ts packages/alchemy/src/Cloudflare/index.ts packages/alchemy/src/Cloudflare/Workers/Worker.ts packages/alchemy/src/Cloudflare/Workers/InferEnv.ts
• node_modules/.bin/tsc -b packages/alchemy/tsconfig.json --pretty false
• git diff --check

[Dawsson]

Closing this in favor of #238. That PR covers the same Rate Limit binding support and is more complete: it includes the binding policy, init-phase RateLimit.bind(...) path, provider wiring, and tests.