fix: stream Claude Code tool input while it is generated (#19837)

## Background

Claude Code harness users received no stream parts while large tool
inputs were generated, delaying visibility until the complete tool call
arrived.

## Root Cause

The Claude bridge tracked only text and thinking content blocks, so
tool_use input_json_delta events had no partial-block state and were
discarded; the captured reproduction confirmed 12 provider deltas
produced zero tool-input events. The harness stream protocol also lacked
tool-input variants needed to transport them.

## Summary

Added tool-input start, delta, and end handling across the Claude
bridge, harness wire schema, host subscriptions, and agent stream
translation, with patch changesets for both published packages.

## Testing

Added regression coverage for Claude tool-input emission, bridge schema
validation, stream translation, and type compatibility with
LanguageModelV4 stream parts.

## End-to-end Validation

- `replay_original_reproduction`: passed; all 12 captured tool-input
deltas streamed and the original bug signal disappeared.
- `pnpm -C examples/ai-functions exec tsx
src/harness-agent/claude-code/file-edit.ts`: live validation was blocked
by a Vercel Sandbox 403 authentication failure.

## Related Issues

Fixes #19695

Closes #19718

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Co-authored-by: ai-sdk-factory <308175966+ai-sdk-factory@users.noreply.github.com>
Co-authored-by: brightiron <95196612+brightiron@users.noreply.github.com>
Co-authored-by: Felix Arntz <3531426+felixarntz@users.noreply.github.com>
Co-authored-by: Felix Arntz <felix.arntz@vercel.com>