Initial scaffold: @ng-eventually/client — SDK-shaped polyfill over NextGraph

Generic polyfill layer that makes a single NextGraph broker behave like the
not-yet-shipped multi-user NextGraph (emulated capabilities + inbox). Zero app domain.

@ng-eventually/client exposes an SDK-identical surface (ng, useShape, inbox); the
polyfill bootstrap (configure + capability helpers) is isolated under /polyfill, so
the main entry stays a drop-in for @ng-org/web|orm. The real SDK is injected at
configure() (no hard import → build-alias safe + testable).

Scaffold: NextGraph wiring stubbed with TODO; capability helpers implemented and
unit-tested (4 tests, typecheck clean). The global-index curator is deferred — in
NextGraph apps/services are mono-user with no global data.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

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+# ng-eventually
+
+A **generic polyfill layer** over the [NextGraph](https://nextgraph.org) JS SDK.
+
+NextGraph's JS SDK does not yet expose cross-wallet reads, capabilities, inboxes
+or group stores. `ng-eventually` lets an app behave as if those existed today, by
+emulating them on top of a **single shared wallet / broker**. It is **generic**:
+it contains **no application domain** — the consumer injects its shapes and the
+*acts* of granting access.
+
+The name: *eventually* NextGraph will ship these features; until then this layer
+fills the gap (and nods at eventual consistency / events).
+
+## Packages
+
+| Package | Role | At migration |
+|---|---|---|
+| **`@ng-eventually/client`** | **SDK-identical** wrapper the app imports instead of `@ng-org/web` / `@ng-org/orm`. Adds the polyfills the broker/verifier will do natively (shared-wallet login, capability enforcement, anticipated cap/inbox methods). | Disappears: the app points back at the real SDK (build alias removed). |
+
+> **A global-index curator package is deferred.** NextGraph is **mono-user with
+> no global data** (apps/services see only what the user shares; there is no
+> multi-user backend). A global index would come from a **singleton app**
+> (a global document administered by the developer) — **not implemented and
+> uncertain**, and simpler paths may exist. So no second package for now; it will
+> be (re)introduced once the global-index mechanism is decided. The curator must
+> never be bundled in the client → it will be a separate package when it lands.
+
+## Design principle
+
+The application code is written **as if the target NextGraph existed**. All
+compensation lives here, *beside* the app. Migration = remove this layer; the
+app code (SDK-shaped) is unchanged.
+
+- **SDK-identical surface**: the client wraps the real `ng` (a Proxy that
+  forwards everything and overrides only what must be emulated) and `useShape`.
+  The real SDK is **injected** via `configure()` (no hard import → build-alias
+  safe + testable).
+- **Authorization = emulated capabilities**: documents carry grants; the client
+  enforces them generically (read filter + write guard). The app *attaches*
+  grants via cap operations — same as it will in the target. No policy is
+  injected.
+- **Inbox**: the client `inbox.post()` deposits; materialization (the curator)
+  is deferred with the global-index mechanism — see the note above.
+- **Tests** of the polyfill (against a real broker) live **in this repo**, so
+  the consuming app can test its features against a mocked, clean API.
+
+## Status
+
+Scaffold. Mechanisms are stubbed with `TODO(broker)` / `TODO(polyfill)` where
+real NextGraph wiring is required.