fix: add security warning for raw PRIVATE_KEY usage in launch-token guide

[schoolkamsergj]

Summary

Fixes #1357

The launch-token guide used vm.envUint("PRIVATE_KEY") to load a private key directly from a .env file, but provided no security warning about the risks — while the deploy-smart-contracts guide on the same site explicitly recommends cast wallet import deployer --interactive as the safer approach and warns: "Never share or commit your private key."

This inconsistency could lead developers (especially those new to Foundry) to accidentally expose their private keys in local .env files or commit them to version control.

Changes

Added a <Warning> callout directly before the .env configuration block in docs/get-started/launch-token.mdx:

• Clearly states the raw PRIVATE_KEY approach is for local development and testing only
• Warns never to commit .env or share the private key
• Links to the deploy-smart-contracts guide for the recommended cast wallet import keystore approach

Why this matters

Both guides are in the same get-started section and developers often follow them together. Without this warning, a developer could reasonably assume the raw env var approach is acceptable for production — leading to potential key exposure.

This is a minimal, targeted fix that resolves the inconsistency without rewriting either guide.

[cb-heimdall]

🟡 Heimdall Review Status

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[cb-heimdall]

Review Error for Jhosepin @ 2026-05-02 00:35:39 UTC
User failed mfa authentication, either user does not exist or public email is not set on your github profile. \ see go/mfa-help

[knisaci]

Thanks for picking this up! I'd also suggest mentioning in the note that .env files should be added to .gitignore to prevent accidental key commits — might be worth adding while this is open.