Prepare final arXiv submission

[aadarwal]

What changed

• Replaced the manuscript abstract with the author-approved final version, applying only the stated mechanical grammar fixes.
• Fixed the manuscript date to July 29, 2026 so arXiv recompilation does not substitute a later build date.
• Removed the two Figure 1 caption sentences that had regressed after their earlier requested removal.
• Recompiled and updated assets/pixcell-paper.pdf.

Validation

• Built a minimal arXiv source archive and compiled it from a fresh extraction.
• Confirmed the regenerated bibliography matches the manuscript bibliography byte-for-byte.
• Confirmed all 17 included table/figure dependencies are present.
• Confirmed 16 pages, embedded fonts, and no undefined citations, undefined references, overfull boxes, or fatal TeX errors.
• Visually inspected every page of the compiled PDF.
• Confirmed the plain-text abstract is ASCII and 1,684 characters, below arXiv's 1,920-character metadata limit.

No CI configuration or test files were changed.