…3486)

## Background

The Azure provider's image generation test fixtures contained a full
1.7MB cartoon raccoon PNG encoded as base64. This appeared in three
places: the streaming chunks fixture (6.9MB), the JSON fixture (2.1MB),
and the resulting snapshot (2.3MB), totaling ~11.3MB. The tests only
validate streaming behavior and response structure, not image content,
so the actual image payload is irrelevant.

In CI (Node 22), the `should stream image generation tool results
include` test was taking **3–10 seconds** due to parsing and streaming
this data, compared to ~1–14ms for every other test in the file.

## Summary

- Replaced full-size base64 PNG with a minimal 1x1 pixel PNG (69 bytes)
in both `azure-image-generation-tool.1.chunks.txt` and
`azure-image-generation-tool.1.json`
- Updated corresponding test snapshots

| File | Before | After |
|---|---|---|
| `azure-image-generation-tool.1.chunks.txt` | 6.9 MB | 12.6 KB |
| `azure-image-generation-tool.1.json` | 2.1 MB | 1.7 KB |
| `azure-openai-provider.test.ts.snap` | 2.3 MB | 200 KB |
| **Total** | **~11.3 MB** | **~214 KB** |

## Manual Verification

All 55 tests in `azure-openai-provider.test.ts` pass on both node and
edge configurations. The target test went from 171ms to 2ms locally.

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Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>