concore validate reports errors but still exits successfully + doesn’t actually check file existence (docs mismatch) #303

Hi @pradeeban ,
I noticed a gap between what concore validate claims to check and what it actually enforces.

The CLI README says validate checks file references and naming conventions. But in the current implementation, the validator collects errors and prints them, yet still exits with code 0, and it doesn’t actually verify whether the node source files exist (the inspect command does that, but validate doesn’t).

This makes concore validate hard to use in CI or pre‑commit checks, because workflows with real errors still look “successful” from the exit code.

What I expected

• If validation errors are found, the CLI should exit non‑zero.
• Optional: Validate node source file existence (defaulting to src/ like other commands).

What I’m seeing

Errors are printed, but the command completes successfully.
Missing node files aren’t flagged as errors (only inspect checks that).

People will rely on concore validate before running or in CI. If it always exits 0, it can silently let broken workflows through.

What i am thinking is that to

• Return a structured result from validate_workflow (e.g., counts of errors/warnings).
• In the CLI command, exit non‑zero when errors exist (sys.exit(1) or raise an exception).
• Validate node file existence relative to the workflow’s directory and the source folder (default src/), and report missing files as errors.
• Update tests to assert non‑zero exit code on validation errors, and add a test that fails when a referenced file is missing.