Pot să vibecodez Google Gemini?

Build me a personal chat client on the Gemini API to replace my Google AI Pro
subscription with per-token billing. Requirements:

- A local web app: Node + Express + better-sqlite3, one page, binds to
  localhost.
- Gemini API key in .env, with optional Claude and OpenAI keys too; a model
  picker per conversation.
- Streaming responses with Markdown and code-block rendering; history in SQLite
  with FTS5 search across old conversations.
- Upload PDFs and images and pass them through to models that accept them.
- System-prompt presets as .md files in ./prompts/, selectable per chat.
- Export any conversation to a Markdown file.
- No accounts, no telemetry; history stays on my machine, only prompts go to
  the APIs.
- Out of scope: Gmail, Docs, and Drive integrations, and mobile apps. Do not
  build Google Workspace OAuth; that ecosystem tie-in is the subscription.
- README: where to create each API key, a rough cost table per model, and state
  that per-token billing can land above or below $20/month depending on use,
  the model itself is only rentable.