refactor(examples): port custom validation to TypeScript

[kmbroai]

Summary

Remove Python from the custom-validation demo. Compile the typed app and HTTP validator through the existing SDK build command, then execute the generated JavaScript on the supported Node.js runtime.

Changes

• Replace the two Python example files with typed .mts sources and keep generated JavaScript untracked.
• Reuse node --run build:examples -- --outDir <target> in the demo runner and its test, with the SDK as the build working directory.
• Preserve the synthetic invoice ownership flaw, authentication controls, proof JSON, server cleanup, and compilation into the temporary scan target.
• Update validation prompts and documentation and include the example in strict type and formatting checks.

Testing

• The focused generated HTTP-proof test passed with five assertions on Node 22.13.0.
• SDK/MCP type checks, SDK formatting, runner formatting, the documented SDK build, and runner help from outside the checkout passed.
• Default and custom output paths, including a path containing spaces, produced identical compiled files. Compiler diagnostics and the stop-before-scan failure guard were preserved.
• Earlier comparisons verified the original Python proof JSON and failure-path server cleanup. A live model-backed scan was not run.

Risk and rollout

Stacked on #768. The demo uses existing SDK development dependencies, synthetic data, and an ephemeral loopback HTTP server. Build failures now use the Node script runner's exit status: the checked compilation failure returns 1 instead of the compiler's 2, with the same diagnostics and no scan start. This PR removes two Python files.

Public disclosure review

• No customer, partner, prospect, or user identities, data, or identifying details are included.
• No credentials, personal data, private source, scan findings, or nonpublic links or tickets are included.
• I reviewed the branch name, title, description, commits, changes, comments, logs, screenshots, attachments, and links for public disclosure.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
🔒 Security Review	✅ Completed 2026-09-04T23:33:56.654176Z	c6eafac	New commits

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[mldangelo-oai]

The compiled example preserves the authentication controls and proof output, and the HTTP validation and server cleanup test passes locally. No actionable findings in the example migration.

[mldangelo-oai]

The migration behavior remains sound; one non-blocking single-source simplification is inline.