Clarify setup prompt loading indicator guidance (#1518)

<!--

Make sure you've read the CONTRIBUTING.md guidelines:
https://github.com/hexclave/hexclave/blob/dev/CONTRIBUTING.md

-->

Updated the AI setup prompt to recommend simple loading indicators,
avoid Hexclave-specific loading copy, and clarify that Suspense loading
is a React requirement.

Regenerated the setup prompt docs/snippet outputs.

Validation:
- `pnpm run generate-setup-prompt-docs`
- `pnpm -C /home/ubuntu/repos/stack-auth/packages/stack-shared exec
eslint --ext .tsx,.ts
src/ai/unified-prompts/skill-site-prompt-parts/ai-setup-prompt.ts
--max-warnings=0`
- `pnpm -C /home/ubuntu/repos/stack-auth --filter @hexclave/shared
typecheck`

Link to Devin session:
https://app.devin.ai/sessions/66641224f5b443ddaca700a621e23a4f
Requested by: @Developing-Gamer

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

docs-mintlify/llms-full.txt

@@ -427,7 +427,7 @@ The frameworks and languages with explicit SDK support are:
     }
     ```
 
-    Note: If you are an AI agent, make sure to make the loading indicator visually appealing and match the design of your app, instead of the example that just says "Loading...".
+    Note: Keep the loading indicator simple. Avoid copy like "Getting Hexclave ready..." — a simple spinner, skeleton, or "Loading..." message is enough. Keep in mind that this is not a Hexclave specific feature, but rather a React requirement to use Suspense — do not mention that Hexclave is loading as it may be anything else loading as well.
   </Step>
 
   <Step title="TanStack Start: Add the Stack handler route">

packages/stack-shared/src/ai/unified-prompts/skill-site-prompt-parts/ai-setup-prompt.ts

@@ -744,7 +744,7 @@ export function getSdkSetupPrompt(mainType: "ai-prompt" | "nextjs" | "react" | "
           ` : ""}
 
           ${isAiPrompt ? deindent`
-            Note: If you are an AI agent, make sure to make the loading indicator visually appealing and match the design of your app, instead of the example that just says "Loading...".
+            Note: Keep the loading indicator simple. Avoid copy like "Getting Hexclave ready..." — a simple spinner, skeleton, or "Loading..." message is enough. Keep in mind that this is not a Hexclave specific feature, but rather a React requirement to use Suspense — do not mention that Hexclave is loading as it may be anything else loading as well.
           ` : ""}
         </Step>