OpenCode runtime, packaging, SQLite, and fetch boundaries

Keep package dependencies one-way: Schema → Core/Protocol; Core/Protocol → Server; Client → Schema/Protocol only; sdk-next composes Client, Core, and Server. Never import Core or Server from Client. Core must support bundled Node CJS and raw TypeScript consumers. Only packages/core/src/db/driver.node.ts may import node:sqlite; other source uses #db/driver for Bun compatibility. Chose Bun node:http(s) transport over undici or Bun fetch because undici@7 hangs under Bun and the gateway needs explicit streaming, backpressure, abort, and listener cleanup; Bun must never import or evaluate undici. Node lazily imports undici.