docs: wasm — core now compiles to wasm32 (all 4 structural items done)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ARCHITECTURE.md

@@ -469,25 +469,23 @@ multi-modal payloads (text inline, audio/photo/data via `iroh-blobs`). Receiving
 - [ ] Private discovery (OPRF/PSI lookup; ZKP ownership proofs).
 - [ ] Capability model (UCAN); offline mailbox.
 - [~] **Web client = `tethercore` on `wasm32`** — relay-only iroh peer, same
-      core, no server bridge. (Correction: it's more *project* than *build
-      target* — see below.)
-      - [x] **Groundwork done** — deps are target-split: native-only transports
-            (tokio-net/mdns/webrtc) + UniFFI + native reqwest under
-            `cfg(not(wasm32))`; wasm gets minimal tokio + fetch-reqwest +
-            wasm-bindgen-futures + iroh (`default-features=false`). SSE/RTC/LAN
-            gated to native; getrandom wasm rng wired. `cargo build --target
-            wasm32-unknown-unknown --features iroh-transport` now reaches
-            tethercore's own code: **15 errors, 4 structural clusters.** Native
-            unaffected.
-      - [ ] **Decouple UniFFI** (10 errs) — the FFI macros are on every public
-            item; gate them out for wasm and add a `wasm-bindgen` surface instead.
-      - [ ] **iroh wasm feature set** (2 errs) — `default-features=false` strips
-            `presets::N0` / `iroh_gossip::net`; find the right wasm features.
-      - [ ] **Runtime** (1 err) — the engine builds a tokio multi-thread runtime;
-            wasm needs `spawn_local` + `?Send` futures (the real refactor — the
-            `Transport`/spawn signatures differ by target).
-      - [ ] **reqwest `.timeout()`** (1 err) — not on the fetch backend; cfg it out.
-      - [ ] Then `wasm-bindgen` + a JS shim; relay-only in-browser (no holepunch).
+      core, no server bridge. **The core now COMPILES to wasm32** (`build-web.sh`
+      → `tethercore.wasm`); native is byte-unaffected.
+      - [x] Deps target-split (native-only transports/UniFFI/native-reqwest under
+            `cfg(not(wasm32))`; wasm gets fetch-reqwest + wasm-bindgen-futures).
+      - [x] **UniFFI decoupled** — all FFI macros `cfg_attr`'d to native; wasm
+            will bind via wasm-bindgen.
+      - [x] **iroh on wasm** — `default-features=false` + `tls-ring` (ring builds
+            for wasm with a wasm clang) + `iroh-gossip/net`; getrandom `wasm_js`.
+      - [x] **Runtime abstraction** — a `Spawner` replaces the tokio `Handle`
+            across `Transport`/Engine: tokio runtime on native, `spawn_local` on
+            wasm. IrohTransport's timers use `n0-future` (no tokio::time on wasm).
+      - [x] reqwest `.timeout()` cfg'd to native.
+      - [ ] **wasm-bindgen JS surface + browser shim** — expose Engine/handler to
+            JS, then a minimal browser smoke test. Relay-only in-browser
+            (no holepunch in the sandbox).
+      - [ ] Toolchain note: the wasm build needs a wasm-capable clang for ring
+            (Homebrew LLVM) + the getrandom rustflag — both wired in `build-web.sh`.
 - [ ] **Retire the Go server** once IrohTransport wins — replace with a
       self-hosted iroh-relay (supernode #1) + a tiny gossip-bootstrap rendezvous.