Examples: canonical programs + golden outputs

[JROChub]

Context

• We have a few examples, but no canonical examples with expected outputs to guide new contributors.

Goal

• Add a small suite of examples with golden outputs and simple verification.

Proposal

• Add 5-8 example programs in examples/ (control flow, types, functions).
• Add expected outputs (e.g., examples/expected/ or inline in tests).
• Add a test that runs each example and compares output.

Acceptance criteria

• New examples are documented in README.md or SPEC.md.
• Tests fail on output mismatch.
• make test passes.