Merge commit '36c66dd290d3ce6eb1ccd310d0c658d4a32bb8eb' as 'repos/effect'

repos/effect/migration/runtime.md

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+# Runtime: `Runtime<R>` Removed
+
+In v3, `Runtime<R>` bundled a `Context<R>`, `RuntimeFlags`, and `FiberRefs`
+into a single value used to execute effects:
+
+```ts
+// v3
+interface Runtime<in R> {
+  readonly context: Context.Context<R>
+  readonly runtimeFlags: RuntimeFlags
+  readonly fiberRefs: FiberRefs
+}
+```
+
+In v4, this type no longer exists and you can use `Context<R>` instead.
+Run functions live directly on `Effect`, and the `Runtime` module is reduced to
+process lifecycle utilities.
+
+## `Runtime.runFork(runtime)` -> `Effect.runForkWith(services)`
+
+In v3, running an effect with dependencies usually meant pulling the current
+runtime from `Effect.runtime<R>()` and calling `Runtime.runFork(runtime)` inside
+the main effect.
+
+**v3**
+
+```ts
+import { Context, Effect, Runtime } from "effect"
+
+class Logger extends Context.Tag("Logger")<Logger, {
+  readonly log: (message: string) => void
+}>() {}
+
+const program = Effect.gen(function*() {
+  const logger = yield* Logger
+  logger.log("Hello from Logger")
+})
+
+const main = Effect.gen(function*() {
+  const runtime = yield* Effect.runtime<Logger>()
+  return Runtime.runFork(runtime)(program)
+}).pipe(
+  Effect.provideService(Logger, {
+    log: (message) => console.log(message)
+  })
+)
+
+const fiber = Effect.runFork(main)
+```
+
+In v4, use the same pattern with `Effect.context<R>()`, then run with
+`Effect.runForkWith(services)`:
+
+**v4**
+
+```ts
+import { Context, Effect } from "effect"
+
+class Logger extends Context.Service<Logger, {
+  readonly log: (message: string) => void
+}>()("Logger") {}
+
+const program = Effect.gen(function*() {
+  const logger = yield* Logger
+  logger.log("Hello from Logger")
+})
+
+const main = Effect.gen(function*() {
+  const services = yield* Effect.context<Logger>()
+  return Effect.runForkWith(services)(program)
+}).pipe(
+  Effect.provideContext(Context.make(Logger, {
+    log: (message) => console.log(message)
+  }))
+)
+
+const fiber = Effect.runFork(main)
+```
+
+If your effect has no service requirements, use `Effect.runFork(effect)`.
+
+## `Runtime` Module Contents
+
+The `Runtime` module now only contains:
+
+- `Teardown` — interface for handling process exit
+- `defaultTeardown` — default teardown implementation
+- `makeRunMain` — creates platform-specific main runners