Build with LLMs

Integrate World ID into my project using IDKit. Here are my app details:

- app_id: app_xxxxx
- rp_id: rp_xxxxx
- action: my-action
- signing_key: (stored as RP_SIGNING_KEY env var)

## Steps

1. Install the IDKit SDK for my platform.

2. Create a backend endpoint that generates RP signatures.
   Signatures verify that proof requests come from my app.
   Use `signRequest({ signingKeyHex, action })` which returns `{ sig, nonce, createdAt, expiresAt }`.
   Never expose the signing key to the client.

3. On the client, fetch the RP signature from my backend, then create an IDKit request with:
   - `app_id`, `action`, and `rp_context` (containing `rp_id`, `nonce`, `created_at`, `expires_at`, `signature`; map the RP signature's `sig`->`signature`, `createdAt`->`created_at`, `expiresAt`->`expires_at`)
   - `allow_legacy_proofs: true`
   - `.preset(proofOfHuman())` for Proof of Human (World ID 4.0, with Orb fallback)
   - Signal is optional — use it to bind context like a user ID or wallet address into the proof. The backend should enforce the same value.

4. On success, send the IDKit result to my backend.
   The backend should forward the payload as-is to: POST https://developer.world.org/api/v4/verify/{rp_id}
   No field remapping is needed.

## Reference
- Full docs: https://docs.world.org/llms.txt