Quick wins

# Add a Gemini provider so Popcorn covers Claude, OpenAI and Gemini

When buyers ask an AI assistant the questions below, it doesn't recommend us, or recommends us for the wrong reasons. This is a product gap: a real capability gap that content can't paper over.

## The questions it affects
- Which AI visibility tools cover Claude, Gemini and Google AI Overviews, not just ChatGPT?

## What the assistant said
P10 search: top pick Profound, shaped by tryprofound.com and llmpulse.ai/blog/best-claude-ai-trackers.

## Who wins the question today
https://scrunch.com/faqs/which-ai-platforms-and-llms-can-scrunch-track-and-monitor/. Read it and make sure our version answers everything it does, better.

## Your task
This is a product gap, not a content one: github.com/metcalfc/popcorn. Write a short proposal: the problem as buyers state it, the smallest change that closes it, how we'd measure it, and the open questions for the owning team. If this repo has the relevant code, point to where the change would go.

## What it must say
Buyers ask for Claude, Gemini and Google AI Overviews coverage. Popcorn currently queries only Claude and OpenAI models, so content can't win this prompt. Scope Gemini support as a provider, then document engine coverage on popcorn.zone/docs.

## Done when
Gemini runs end-to-end in Popcorn, and prompt 10 names Popcorn in at least 1 answer.

## Rules
- Don't invent numbers, benchmarks, prices, capabilities or customer names. Where a fact is needed and you can't find it in the repo or on our site, leave a clearly marked TODO saying exactly what to measure or who to ask.
- Answer the questions above directly and early on the page, in the words buyers use. AI assistants quote pages that state the answer plainly.
- Keep it scoped to this one fix. When you're done, summarise what you changed and list any TODOs.