fix: correct base64 data URI segment count validation in readImage

[ionkorol]

Description

A base64 data URI (e.g. data:image/png;base64,iVBOR...) splits into 2 segments by ,, but the check was comparing against 1, causing all valid base64 image inputs to be rejected.

Introduces a breaking change?

• Yes
• No

Type of change

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Documentation update (improves or adds clarity to existing documentation)
• Other (chores, tests, code style improvements etc.)

Tested on

• iOS
• Android

Testing instructions

• Pass a base64-encoded image data URI to a model that calls readImage and verify it is decoded and processed correctly
• Verify that malformed URIs (no comma, multiple commas) are still correctly rejected

Screenshots

Related issues

Checklist

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly
• My changes generate no new warnings

Additional notes

[msluszniak]

Thank you @ionkorol for your PR, this totally makes sense. I'll test this change tommorow and probably add some test cases to our test suite :)

[msluszniak]

@ionkorol I'm closing this one in favour of #811 as I couldn't make changes to the PR that comes from organisation.