feat: support image URLs (fileUri) in image input fields

[gennadijbgl]

What

Adds URL support to image input fields, mirroring the existing file field's data / fileUri pattern. Images can now be supplied by URL instead of only inline base64.

const analyze = ax('photo:image -> answer:string');

// existing — inline base64
await analyze.forward(llm, { photo: { mimeType: 'image/jpeg', data } });

// new — by URL
await analyze.forward(llm, {
  photo: { mimeType: 'image/jpeg', fileUri: 'https://example.com/photo.jpg' },
});

An image field value now accepts either { mimeType, data } (base64, unchanged) or { mimeType, fileUri } (URL). Supplying both, or neither, is rejected — same rule the file type already enforces.

How

The internal image content block gains a second union member carrying fileUri (parallel to how file is modeled). Each provider maps the URL variant to its native form:

Provider	base64 (existing)	URL (new)
OpenAI	image_url.url = data URI	image_url.url = the URL directly
Anthropic	source: { type: 'base64', … }	source: { type: 'url', url }
Gemini	inlineData: { data }	fileData: { fileUri } (e.g. gs:// / Files API URIs)

Validation (dsp/util.ts, dsp/prompt.ts, ai/validate.ts), content hashing (ai/base.ts), logging (dsp/loggers.ts) and the unsupported-provider content processor (ai/processor.ts) were updated to narrow on the URL variant. AxFieldValue exposes the new shape to callers.

Note on Gemini: fileData.fileUri accepts Google-hosted URIs (Files API / gs://), consistent with the existing file behavior — not arbitrary public http(s) URLs. OpenAI and Anthropic accept public URLs.

Tests

• dsp/prompt.test.ts — image render with data, with fileUri, mixed arrays, and validation (missing mimeType / missing both / both present).
• google-gemini/api.test.ts — request mapping: base64 → inlineData, fileUri → fileData.
• Type-check clean; full unit suite green (the 2 unrelated jsRuntime sandbox failures are a Windows-only Node permission-model artifact).

🤖 Generated with Claude Code

[dosco]

sorry was busy with big changes to multi language codebase will review this in a day or so.