phase 5: wasm core, GalaxyClient skeleton, Connect-Web stubs

Compile `ui/core` to WebAssembly via TinyGo (903 KB) and expose four
canonical-bytes / signature-verification functions on
`globalThis.galaxyCore` from `ui/wasm/main.go`. The TypeScript-side
`Core` interface plus a `WasmCore` adapter (browser + JSDOM loader)
bridge those into a typed shape, and a `GalaxyClient` skeleton wires
`Core.signRequest` → injected `Signer` → typed Connect client →
`Core.verifyPayloadHash` / `verifyResponse`.

Wire `ui/buf.gen.yaml` against the local
`@bufbuild/protoc-gen-es` v2 binary (devDependency) so the codegen
step does not depend on the buf.build BSR. Vitest covers the bridge
end-to-end: per-method WasmCore tests under JSDOM, byte-for-byte
canon parity against the gateway fixtures committed in Phase 3, and
a `GalaxyClient` orchestration test using
`createRouterTransport`. The committed `core.wasm` snapshot tracks
TinyGo output so contributors run `make wasm` only when `ui/core/`
changes; CI consumes the snapshot directly.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/buf.gen.yaml

@@ -0,0 +1,12 @@
+version: v2
+
+# Generates the TypeScript Protobuf-ES + Connect-ES service descriptors
+# from the gateway's authenticated edge .proto files into the SvelteKit
+# frontend's source tree. The plugin runs locally from
+# `frontend/node_modules/.bin/protoc-gen-es` (added as a devDependency
+# in `frontend/package.json`) — no network call to buf.build BSR.
+plugins:
+  - local: frontend/node_modules/.bin/protoc-gen-es
+    out: frontend/src/proto
+    opt:
+      - target=ts