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.