Local development-centric build profile

[PaulRBerg]

The fact that the .cargo/config.toml file is superfluous for local development leads to a bad developer experience. Quoting the README:

The .cargo/config.toml is strictly used for Vercel and you can remove it for local development

We should:

• Remove this file
• Provide the build parameters to Vercel using command-line arguments
• Make the default build settings conform to a local development mode

[PaulRBerg]

Fixed by https://github.com/sablier-labs/v2-merkle-api/pull/22.