feat(sdk): add HttpApi clients and embedded host (#33445)

packages/sdk-next/README.md

@@ -0,0 +1,27 @@
+# @opencode-ai/sdk-next
+
+Effect-native scoped OpenCode host for in-process applications. This transitional package will replace the existing generated `@opencode-ai/sdk` after its consumers migrate.
+
+The SDK executes Server's assembled HTTP router in memory. It opens no listener and performs no network I/O, while preserving the same routing, middleware, handlers, codecs, and errors as the network client.
+
+```ts
+import { OpenCode } from "@opencode-ai/sdk-next"
+
+const opencode = yield * OpenCode.create()
+const session = yield * opencode.sessions.get({ sessionID })
+```
+
+It also exposes local-only `tools.register(...)`. Closing the owning Effect Scope releases router resources, location services, fibers, and scoped tool registrations.
+
+The same constructor is available as a service Layer:
+
+```ts
+const program = Effect.gen(function* () {
+  const opencode = yield* OpenCode.Service
+  return yield* opencode.sessions.get({ sessionID })
+})
+
+yield * program.pipe(Effect.provide(OpenCode.layer))
+```
+
+`OpenCode.layer` adapts `OpenCode.create()` for dependency injection; it does not define another host implementation.