Show requested, fill, and observed slot sizes in GPT diagnostics

[ChristianPavilonis]

Problem

Flexible creatives, especially APS, can report 1×1 through GPT slotRenderEnded.size even when the publisher-visible slot is larger after rendering. Operators need to distinguish the requested slot formats, GPT’s reported fill size, and outer-slot layout geometry.

Proposed behavior

• Preserve the full configured size list Trusted Server supplied to GPT for the correlated request.
• Preserve GPT’s slotRenderEnded.size as the reported fill-size fact.
• For uniquely bound, connected, filled slots, record and display the observed outer CSS slot box after render.
• Keep the observed box updated on resize when supported.
• Reject measurements for ambiguous, unbound, empty, or stale refresh cycles.
• Export all three values and document that cross-origin/SafeFrame content cannot be measured internally.

Acceptance criteria

• ts_console displays the complete requested size list, GPT-reported fill size, and an optional observed outer slot box.
• A GPT-reported 1×1 and a distinct observed outer box are visible together.
• Delayed measurements cannot update a newer request cycle.
• No APS sandbox or creative-iframe access is added.