feat(plugin-kit): @punktfunk/plugin-kit 0.1.0 — the Effect plugin framework

The ~80% of every plugin that was copy-pasted (rom-manager ↔ playnite),
extracted as one Effect-v4 package:

- runtime: definePluginKit — async-main boundary hiding a ManagedRuntime
  (two-effect-instances discipline), signal-driven interruption with a
  bounded shutdown grace
- config: Schema-driven raw round-trip (defaults only in the Schema via
  withDecodingDefaultKey + encodingStrategy omit; file stays authored-shape),
  atomic writes, world-writable refusal, changes stream
- cache-store: disposable derived state, corrupt→empty, write-through
- reconcile: kit-owned provider wire schemas + typed client over the
  skew-safe untyped pf.request seam
- sync-engine: generic poll/watch/debounce/single-flight-coalesce/
  fingerprint-skip engine with a status PubSub (the SSE feed)
- ui-server + sse: effect/unstable/httpapi behind servePluginUi with
  core-only env layers (validated by the phase-0 spikes); raw SSE route
  (httpapi has no event-stream media type)
- cli: minimal command dispatcher reusing the plugin layer graph
  (deliberately not effect/unstable/cli — it needs platform packages)
- react subpath: plugin router (path→hash→fallback deep-link restore +
  pf-ui:navigate bridge), ResultGate, sseAtom, resolvePluginBase
- theme.css: the console's violet identity packaged for plugin UIs

18 bun tests incl. the two phase-0 spikes; publish workflow mirrors
sdk-publish (tag plugin-kit-v*; 0.1.0 published manually).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugin-kit/test/spike-httpapi.test.ts

@@ -43,11 +43,11 @@ const groupLive = HttpApiBuilder.group(api, "spike", (handlers) =>
 		.handle("echo", ({ payload }) => Effect.succeed({ echoed: payload.msg })),
 );
 
-// Core-only environment for HttpApiBuilder: no platform package needed.
-const env = Layer.mergeAll(
-	Etag.layerWeak,
-	Path.layer,
-	HttpPlatform.layer.pipe(Layer.provide(FileSystem.layerNoop({}))),
+// Core-only environment for HttpApiBuilder: no platform package needed. FileSystem is
+// provideMerge'd so both HttpPlatform.layer and HttpApiBuilder see it satisfied.
+const env = Layer.provideMerge(
+	Layer.mergeAll(Etag.layerWeak, Path.layer, HttpPlatform.layer),
+	FileSystem.layerNoop({}),
 );
 
 const appLayer = HttpApiBuilder.layer(api).pipe(