feat: add Soroban CLI network config and deploy pipeline

[OthmanImam]

Add Soroban CLI Network Configuration and Deployment Pipeline

Summary

This PR introduces support for configuring and deploying Soroban smart contracts
within the Contract Fox workspace. It sets up default network profiles, adds a
convenience deploy script, updates documentation, and provides environment
variable templates.

Key Changes

• Soroban config dir: .soroban/config/config.toml with testnet and
  mainnet entries.
• Deployment script: scripts/deploy.sh builds and deploys all contracts
  to a chosen network; automatically adds missing network profiles.
• Docs: new docs/DEPLOY.md detailing network setup, script usage, and
  contract invocation examples.
• Environment template: .env.example updated with
  SOROBAN_RPC_URL and SOROBAN_NETWORK_PASSPHRASE entries.
• Repo metadata: .gitignore updated to ignore .env; README.md links to
  deployment docs and explains Soroban network configuration.

Motivation

Developers need a reliable, reproducible way to deploy contracts to Soroban
public networks. Prior to this work, setup was manual and scattered across
documentation. The added script and configuration centralize these operations and
make onboarding easier.

Testing

• Manual inspection of deploy.sh for syntax and logic (POSIX compliant).
• Verified Makefile already supports deploy-testnet/deploy-mainnet.
• Created .env.example and confirmed .gitignore blocks .env.
• Documentation builds and renders as Markdown.

Usage

chmod +x ./scripts/deploy.sh
./scripts/deploy.sh testnet  # builds and deploys to testnet
./scripts/deploy.sh mainnet # deploys to mainnet

The script prints the contract IDs returned by the Soroban CLI, satisfying the
acceptance criteria.

Notes

• Requires the Soroban CLI to be installed (cargo install soroban-cli).
• On Windows, a POSIX shell (Git Bash/WSL) is necessary to run deploy.sh.

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Closes: #5