fix: document DefaultExpiredAt and remove dead example code

[chrisli30]

Summary

• DefaultExpiredAt: Changed from -1 to 0 with JSDoc explaining the semantic. The backend (executor.go:554) only enforces expiration when expiredAt > 0, so any value <= 0 means "never expire". 0 is cleaner as it matches the protobuf zero value.
• Example cleanup: Removed commented-out createInputData/extractInputData/hasInputData helper functions that were never implemented. The plain object approach below them works fine.

Closes #199, closes #200

Test plan

• yarn build succeeds
• No behavior change — 0 and -1 are both treated as "never expire" by the backend

[claude]

PR Review

This is a small, focused cleanup PR. Both changes are appropriate and overall quality is good.

DefaultExpiredAt value change (workflow.ts:13)

The JSDoc is clear and well-grounded in backend behavior. Switching to 0 aligns with protobuf zero-value semantics — good call.

One minor nit: the import ordering. After the change, line 13 is the export const and line 14 is an import statement:

export const DefaultExpiredAt = 0;
import { WorkflowStatus, WorkflowProps, InputVariables } from '@avaprotocol/types';

Imports are hoisted so this works, but it's non-standard and easy to miss. Since the line is already being touched in this PR, worth moving that import up to join the others at lines 1-7.

Also: DefaultExpiredAt is exported from workflow.ts but does not appear to be re-exported from the package's main index.ts. If it's intended for SDK consumers, it should be in the public API. If it's internal, a short comment to that effect would help.

Dead code removal (examples/example.ts)

Clean and correct. The removed block was a commented-out TODO referencing functions (createInputData, extractInputData, hasInputData) that were never implemented. Removing it entirely is the right call. The emoji annotation cleanup on the trigger input line is also good hygiene.

Summary

• DefaultExpiredAt value + JSDoc: good change, well documented
• Import ordering: minor nit, easy fix while the line is in scope
• DefaultExpiredAt public export: confirm intent (SDK consumer vs internal)
• Dead code removal: clean