chore(monorepo): resolve contracts/middleware workspace mismatch (empty dirs vs actual contract/ crate)

[phertyameen]

Summary

The root package.json declares four workspaces: frontend, backend, contracts, middleware. In reality:

Path	State
contract/	The actual Soroban Rust crate (Cargo.toml, src/lib.rs)
contracts/	Empty directory, declared as npm workspace
middleware/	Empty directory, declared as npm workspace

This mismatch is actively confusing tooling and contributors: npm workspaces point at directories with no package.json, while the Rust crate everyone works in is invisible to workspace tooling and is only discovered through .github/workflows/ci.yml, whose contracts job hard-codes working-directory: contract.

Impact

• npm install/workspace commands silently ignore the Rust code path.
• Contributors following the README monorepo description land in the wrong directory.
• Any future npm run aggregation (build/lint across workspaces) will miss or misreport these areas.

Proposed options

Pick one direction and document it:

1. Rename the Rust crate directory to match expectations (contracts/), updating .github/workflows/ci.yml and ci-cd.yml (working-directory, Swatinem/rust-cache workspaces key), or
2. Keep contract/ and remove contracts/middleware from workspaces until they have content, documenting the layout in README.md.

Acceptance criteria

• Exactly one canonical location for the smart-contract crate.
• All workflow files reference that location consistently.
• package.json workspaces contains only directories that exist and are used.