Fix SVG Creative Display & Code Quality Improvements

[aram356]

Resolves

• Closes Fix SVG Creative Display #12

Summary

• Fixed SVG creatives not rendering correctly due to oversized caption text on tall banners (300x600)
• Reduced CAPFONT calculation to cap at 16px instead of scaling too large
• Removed overflow:hidden from SVG that was clipping content

Other Changes

Code Quality

• Replaced runtime HashMap with compile-time phf_map! for SIZE_MAP (zero-cost initialization)
• Consolidated duplicate build_openrtb_response functions into single implementation
• Fixed side-effect mutation in .map() with idiomatic let-else pattern
• Fixed unwrap() after is_none() check anti-pattern
• Removed dead escape_html function
• Renamed MAX_AREA_CPM → MAX_AREA_BONUS for clarity

New Features

• Added /_/sizes endpoint returning JSON with all standard ad sizes
• Added decode_aps_price() function for base64 price decoding
• Added standard_sizes() iterator for programmatic size access

Testing

• Added Playwright E2E test suite for creative visibility
• Added playwright job to GitHub Actions CI
• Tests verify SVG creatives render correctly for 13 standard sizes

Documentation & Housekeeping

• Updated README with sizes table, /_/sizes API docs, and test instructions
• Added nodejs 24.12.0 to .tool-versions
• Added Node/Playwright entries to .gitignore

Test plan

• cargo test passes
• Playwright E2E tests verify SVG visibility at all standard sizes
• Visual inspection of 300x600 banner shows properly sized caption

[ChristianPavilonis]

I was considering this for my docker build but thought we were going to make edge zero public. Are we holding off on that for any reason?

[aram356]

I am not against it. We can make Github repo open for now. Let's agree on this together.

[ChristianPavilonis]

I'm for it!

[ChristianPavilonis]

One thing we should consider doing is adding some info to the creatives.
For example we could add "✔︎ OpenRTB request signed" or "ℹ️ Mock APS creative" so we can demo and test easy without tailing.

[aram356]

One thing we should consider doing is adding some info to the creatives. For example we could add "✔︎ OpenRTB request signed" or "ℹ️ Mock APS creative" so we can demo and test easy without tailing.

This is a good idea. Make it a ticket?

We can also add some more meta to HTML comments if it too much to display in a banner

Done: #14