fix(ocr): sort boxes within a row left-to-right

[msluszniak]

Description

This is potentially a blocker for demo app recordings for promotion purposes.

useOCR().forward(image) returned boxes top-to-bottom but boxes on the same visual row fell back to the earlier descending-side-length ordering — reading as "by probability" rather than reading order.

After the final Y-sort in groupTextBoxes, group consecutive boxes whose top-Y differs by less than half the mean text height and sort each group left-to-right by top-X.

Single-comparator soft-Y-equality is intentionally avoided — A~B, B~C with A far from C violates strict weak ordering and is UB under std::sort.

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

1. Run the computer-vision demo → OCR screen.
2. Pick a photo with multiple short tokens on the same line (e.g. Price 12.99 USD).
3. Inspect the results list — tokens within a row now come out left-to-right.

Related issues

Closes #1159