docs(workflow): add deterministic execution requirement

[Mistat]

Summary

• Document that .trigger() uses a suspend/resume execution model and job code must be deterministic
• Add concrete examples of correct and incorrect usage patterns (loops, timestamps, external API calls)
• Explain that non-deterministic arguments (e.g., Date.now(), external API responses) cause argument hash mismatch errors

Background

The Rust runtime (service/function/runtime/src/engine/ops/job.rs in platform-core-services) enforces deterministic execution by verifying arg_hash on resume. This critical constraint was not documented, risking users encountering unclear errors.

Test plan

• Verify documentation builds and renders correctly
• Confirm code examples are consistent with existing documentation style

🤖 Generated with Claude Code

[toiroakr]

I thought it might be even better if there were examples of how to rewrite the "bad" examples.

// ❌ Bad: non-deterministic — argument changes between executions
await processJob.trigger({ timestamp: Date.now() });

↓

// ✅ OK: call Date.now() in separated job
const timestamp = await timestampJob.trigger();
await processJob.trigger({ timestamp });

// ❌ Bad: non-deterministic — external data may change between executions
const items = await fetch("https://api.example.com/items").then((r) => r.json());
for (const item of items) {
  await processItem.trigger({ id: item.id });
}

↓

// ✅ OK: call fetch("https://api.example.com/items").then((r) => r.json()); in separated job
const items = await fetchItemsJob.trigger();
for (const item of items) {
  await processItem.trigger({ id: item.id });
}

[anukiransolur]

This change will be added in SDK repository 945