Add Effect v4 support, Fast Refresh tooling, and revamped docs (#56)

## Summary

- Add `effect-fc-next`, a React 19 integration targeting Effect v4 beta.
- Introduce component lifecycles, scoped resources, queries, mutations, forms, lenses, views, and refreshable components.
- Add `@effect-view/vite-plugin` for Vite Fast Refresh support.
- Add an Effect v4 example application covering the new APIs.
- Expand test coverage for both the existing and next-generation packages.
- Replace the starter Docusaurus content with complete Effect View documentation while preserving the Effect v3 docs as a versioned snapshot.
- Update the landing page, navigation, package scripts, and build output.
- Extend CI with linting, tests, package builds, Docker builds, and container publishing.

## Validation

- `bun lint:tsc`
- `bun lint:biome`
- `bun test`
- `bun run build`
- `bun pack`
- Docker image build

---------

Co-authored-by: Julien Valverdé <julien.valverde@mailo.com>
Reviewed-on: Thilawyn/effect-fc#56

packages/effect-fc/src/Lens.test.tsx

@@ -0,0 +1,171 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react"
+import { Effect, Layer, SubscriptionRef } from "effect"
+import * as React from "react"
+import { describe, expect, it } from "vitest"
+import * as Component from "./Component.js"
+import * as Lens from "./Lens.js"
+import * as ReactRuntime from "./ReactRuntime.js"
+
+
+const makeRuntime = async () => {
+    const runtime = ReactRuntime.make(Layer.empty)
+    const effectRuntime = await Effect.runPromise(runtime.runtime.runtimeEffect)
+
+    return {
+        runtime,
+        effectRuntime,
+        dispose: () => Effect.runPromise(runtime.runtime.disposeEffect),
+    }
+}
+
+const expectDefined = <A,>(value: A | undefined): A => {
+    if (value === undefined)
+        throw new Error("Expected value to be defined")
+    return value
+}
+
+describe("Lens", () => {
+    it("useState stays in sync with lens updates in both directions", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const ref = await Effect.runPromise(SubscriptionRef.make(0))
+        const lens = Lens.fromSubscriptionRef(ref)
+
+        const Probe = Component.makeUntraced("LensUseStateProbe")(function*() {
+            const [value, setValue] = yield* Lens.useState(lens)
+
+            return (
+                <>
+                    <div>{value}</div>
+                    <button type="button" onClick={() => setValue(previous => previous + 1)}>increment</button>
+                </>
+            )
+        }).pipe(
+            Component.withRuntime(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("0")
+
+        await Effect.runPromise(Lens.set(lens, 5))
+        await screen.findByText("5")
+
+        fireEvent.click(screen.getByRole("button", { name: "increment" }))
+        await screen.findByText("6")
+        expect(await Effect.runPromise(Lens.get(lens))).toBe(6)
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useState respects the provided equivalence when subscribing to lens changes", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        const ref = await Effect.runPromise(SubscriptionRef.make({ id: 1, label: "first" }))
+        const lens = Lens.fromSubscriptionRef(ref)
+
+        const Probe = Component.makeUntraced("LensUseStateEquivalenceProbe")(function*() {
+            const [value] = yield* Lens.useState(lens, {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withRuntime(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+
+        await Effect.runPromise(Lens.set(lens, { id: 1, label: "ignored" }))
+        await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
+        expect(screen.queryByText("ignored")).toBeNull()
+
+        await Effect.runPromise(Lens.set(lens, { id: 2, label: "updated" }))
+        await screen.findByText("updated")
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useFromReactState writes React state changes into the returned lens", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        let lens: Lens.Lens<string, never, never, never, never> | undefined
+
+        const Probe = Component.makeUntraced("LensUseFromReactStateProbe")(function*() {
+            const [value, setValue] = React.useState("hello")
+            const reactLens = yield* Lens.useFromReactState([value, setValue])
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <button type="button" onClick={() => setValue(previous => `${previous}!`)}>{value}</button>
+        }).pipe(
+            Component.withRuntime(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("hello")
+        await waitFor(() => expect(lens).toBeDefined())
+
+        fireEvent.click(screen.getByRole("button", { name: "hello" }))
+        await screen.findByText("hello!")
+        await waitFor(async () => expect(await Effect.runPromise(Lens.get(expectDefined(lens)))).toBe("hello!"))
+
+        view.unmount()
+        await dispose()
+    })
+
+    it("useFromReactState respects equivalence when lens updates flow back into React state", async () => {
+        const { runtime, effectRuntime, dispose } = await makeRuntime()
+        let lens: Lens.Lens<{ readonly id: number; readonly label: string }, never, never, never, never> | undefined
+
+        const Probe = Component.makeUntraced("LensUseFromReactStateEquivalenceProbe")(function*() {
+            const [value, setValue] = React.useState({ id: 1, label: "first" })
+            const reactLens = yield* Lens.useFromReactState([value, setValue], {
+                equivalence: (self, that) => self.id === that.id,
+            })
+
+            yield* Component.useOnMount(() => Effect.sync(() => {
+                lens = reactLens
+            }))
+
+            return <div>{value.label}</div>
+        }).pipe(
+            Component.withRuntime(runtime.context)
+        )
+
+        const view = render(
+            <runtime.context.Provider value={effectRuntime}>
+                <Probe />
+            </runtime.context.Provider>
+        )
+
+        await screen.findByText("first")
+        await waitFor(() => expect(lens).toBeDefined())
+
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 1, label: "ignored" }))
+        await waitFor(() => expect(screen.getByText("first")).toBeTruthy())
+        expect(screen.queryByText("ignored")).toBeNull()
+
+        await Effect.runPromise(Lens.set(expectDefined(lens), { id: 2, label: "updated" }))
+        await screen.findByText("updated")
+
+        view.unmount()
+        await dispose()
+    })
+})