fix: prevent Pi turns from deadlocking on multiple host tool approvals in one step (#19309)

## Background

A Pi step containing two approval-required host tool calls exposed only
the first approval, leaving the resumed turn permanently waiting for the
second result.

## Root Cause

runPrompt paused and abandoned the event reader after the first host
approval because the protocol did not communicate the step's tool-call
cardinality, while Pi's journal and resume barrier retained and awaited
both calls. The recorded reproduction and source tracing confirmed this
mismatch.

## Summary

Added an optional step tool-call count to the harness protocol, made Pi
emit the known count, and made runPrompt collect all counted approval or
result requests before pausing. Added patch changesets for both
published packages.

## Testing

Added regression coverage for Pi's parallel tool-call count translation
and for surfacing every approval from a counted step, including protocol
type coverage.

## End-to-end Validation

- `pnpm -C examples/ai-functions exec tsx --input-type=module --eval
"<recorded reproduction source>"` exited successfully and reported that
both approval requests were surfaced with no deadlock.

## Related Issues

Fixes #19302

Closes #19304

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Co-authored-by: ai-sdk-factory <308175966+ai-sdk-factory@users.noreply.github.com>
Co-authored-by: orcunbalcilar <77508227+orcunbalcilar@users.noreply.github.com>