feat: port runnable TypeScript core examples and smoke coverage

[rlippmann]

Summary

• port Python 0.5 core examples to TypeScript under examples/
• make examples directly runnable from built scripts via node on dist/examples/*.js
• add lightweight smoke tests that build once and execute each built example script

Scope

• examples and examples README
• example smoke test coverage
• minimal build-output wiring needed so examples are emitted to dist/examples

Out of scope

• no engine/runtime behavior changes
• no fixture corpus changes
• no REPL or preprocessor work

Verification

• npm run build
• node dist/examples/01_persistent_guardrails.js
• node dist/examples/02_configuration_and_correction.js
• node dist/examples/03_ambiguity_with_clarification.js
• node dist/examples/04_tool_governance_denylist.js
• node dist/examples/05_llm_integration_pattern.js
• node dist/examples/06_transcript_replay.js
• node dist/examples/07_single_policy_correction.js
• npm run test