Add regional endpoint selection with GatewayArea support

[fern-support]

Add regional endpoint selection with GatewayArea support

Summary

This PR adds area-based URL selection to the Python SDK, mirroring the functionality added to the Go SDK in this commit.

The implementation creates wrapper clients (RegionalAgora/AsyncRegionalAgora) that extend the base Fern-generated clients, then exports them as Agora/AsyncAgora so users get the enhanced functionality transparently.

New exports:

• GatewayArea enum: US, EU, APAC, CN
• RegionalEndpointPool: For advanced users who want to manage the pool lifecycle

Usage:

from agoraio import Agora, GatewayArea

client = Agora(
    gateway_area=GatewayArea.US,
    username="YOUR_USERNAME",
    password="YOUR_PASSWORD",
)

Files added to .fernignore to prevent Fern from overwriting manual changes.

Updates since last revision

• Fixed regional URL path: Added /api/conversational-ai-agent suffix to regional URLs (e.g., https://api-us-west-1.agora.io/api/conversational-ai-agent) to match the default environment URL structure
• Verified with test credentials: Successfully connected to regional endpoint and called agents.list() API (returned 0 agents, confirming connectivity works)

Review & Testing Checklist for Human

• Verify domain configuration matches Go SDK - Check that region prefixes (api-us-west-1, api-cn-east-1, etc.) and domain suffixes (agora.io, sd-rtn.com) match the Go implementation exactly
• DNS resolution is synchronous - select_best_domain() calls socket.getaddrinfo() during client init. Verify this is acceptable behavior (could block if DNS is slow)
• Base URL resolved once at construction - The URL is computed once in __init__ and passed to parent. Calling endpoint_pool.next_region() later won't update the client's base URL. Confirm this is the intended behavior.
• Test the import aliasing - Verify from agoraio import Agora returns RegionalAgora and that existing code without gateway_area still works

Recommended test plan:

1. Install the SDK locally: pip install -e .
2. Test basic import: from agoraio import Agora, GatewayArea, RegionalEndpointPool
3. Create a client with gateway_area=GatewayArea.US and verify the base URL is https://api-us-west-1.agora.io/api/conversational-ai-agent
4. Create a client without gateway_area and verify it falls back to default environment
5. Make an API call to verify connectivity

Notes

• No unit tests included in this PR
• The TypeScript SDK PR is being created separately
• CI compile and tests are passing

Link to Devin run: https://app.devin.ai/sessions/3f033f4523f94c2384477ddfc79d00a8
Requested by: blank@buildwithfern.com (@fern-support)

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

⚙️ Control Options:

• Disable automatic comment and CI monitoring