Correct the conformance polyglot command

[rmcdaniel]

Fix

Correct the public conformance runbook's Polyglot command. Sample App provides scripts/polyglot.sh. The listed scripts/polyglot-validation.sh does not exist.

Follow-up to #122's executable-instruction audit. This patch corrects the command and retains the experiment's scope.

Verification

Checked Sample App's current main file inventory and its polyglot validation workflow, which invokes scripts/polyglot.sh. The latest merged-main published-artifact smoke passes with CLI 2.1.3, Server 2.4.31 and the frozen PHP/Python/Rust SDK tuple. Normal shared repository checks are required for this documentation change. No prose-mirroring test is added.

[rmcdaniel]

Reviewed the complete one-line diff at 1b87990cd994c4624f8b0d3d2a731c7cd57edc1b. The corrected command exists in Sample App's current main and is invoked by its ordinary published PHP/Python/Rust smoke workflow. The latest exact-consumer smoke passes in run 36719012982. This patch changes the executable instruction without changing scenario scope or adding a compatibility claim. Merge after normal Shared contract tests pass, then verify the public document and remote-branch deletion.