Http fetch checker (#219)

## 💸 TL;DR
<!-- What's the three sentence summary of purpose of the PR -->

Interactive domain checker for devs to see if their domain is allowed or
not. Also will suggest domains we allowlist based on what they are
trying to make. NO AI, this is purely deterministic.

Author: vdikransamarjian

docs/capabilities/http-fetch.md docs/capabilities/http-fetch.mdxdocs/capabilities/http-fetch.md renamed to docs/capabilities/http-fetch.mdx

@@ -1,3 +1,5 @@
+import FetchDomainChecker from "@site/src/components/FetchDomainChecker";
+
 # HTTP Fetch
 
 Make requests to allow-listed external domains.
@@ -28,6 +30,8 @@ Apps may request a domain to be added to the allow-list by specifying domains in
 
 Requested domains will be submitted for review when you playtest or upload your app. Most domain requests are reviewed within **1–2 business days**, though requests with policy ambiguity may take longer. Admins may approve or deny domain requests.
 
+<FetchDomainChecker />
+
 Domain entries must be exact hostnames only, such as nytimes.com or wikipedia.org. These fetch requests are not allowed:
 
 - Be specific. No using \*.example.com when you need api.example.com

docs/guides/faq.mdx

@@ -175,7 +175,7 @@ Most app versions are reviewed within **1–2 business days**. New apps or versi
 
 - **Payments**: apps using the payments capability go through additional policy review.
 - **`runAs: 'USER'`**: user action permissions require explicit approval as part of the review.
-- **External fetch domains**: new domain requests are reviewed separately under the same **1–2 business day** target, though requests with policy ambiguity may take longer (see [HTTP Fetch](../capabilities/http-fetch.md)).
+- **External fetch domains**: new domain requests are reviewed separately under the same **1–2 business day** target, though requests with policy ambiguity may take longer (see [HTTP Fetch](../capabilities/http-fetch.mdx)).
 
 To keep review moving:
 
@@ -454,10 +454,10 @@ Domain requests are reviewed separately from app publishing. Most domain request
 To make approval go smoothly:
 
 - Use exact hostnames only — no wildcards (`*.example.com`), no protocols (`https://`), and no paths (`api.example.com/webhooks`).
-- Add a "Fetch Domains" section to your app [`README.md`](../devvit_rules.md#app-readme-requirements) listing each domain and explaining why you need it. The expected format is documented in [HTTP Fetch](../capabilities/http-fetch.md).
+- Add a "Fetch Domains" section to your app [`README.md`](../devvit_rules.md#app-readme-requirements) listing each domain and explaining why you need it. The expected format is documented in [HTTP Fetch](../capabilities/http-fetch.mdx).
 - Include links to your Terms and Conditions and Privacy Policy in your app details form.
 
-Before submitting, check the [global fetch allowlist](../capabilities/http-fetch.md#global-fetch-allowlist) — if your domain is already listed there, no separate request is needed. Personal domains (e.g., `personaldomain.com`) aren't approved.
+Before submitting, check the [global fetch allowlist](../capabilities/http-fetch.mdx#global-fetch-allowlist) — if your domain is already listed there, no separate request is needed. Personal domains (e.g., `personaldomain.com`) aren't approved.
 
 </details>