Add delay parameter to crawl options in all SDKs (#1514)

* Add delay parameter to crawl options in all SDKs

Co-Authored-By: mogery@sideguide.dev <mogery@sideguide.dev>

* Update terminology from 'between crawl requests' to 'between scrapes'

Co-Authored-By: mogery@sideguide.dev <mogery@sideguide.dev>

* Apply suggestions from code review

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: mogery@sideguide.dev <mogery@sideguide.dev>
Co-authored-by: Gergő Móricz <mo.geryy@gmail.com>

apps/rust-sdk/src/crawl.rs

@@ -138,6 +138,8 @@ pub struct CrawlOptions {
     #[serde(skip)]
     pub idempotency_key: Option<String>,
 
+    pub delay: Option<u32>,
+
     /// When using `FirecrawlApp::crawl_url`, this is how often the status of the job should be checked, in milliseconds. (default: `2000`)
     #[serde(skip)]
     pub poll_interval: Option<u64>,