Live dashboard: replace data loaders with client-side polling

CORS: add CORSMiddleware to FastAPI for localhost:3000 so browser fetch
works across ports without errors.

All four pages now use async generator cells that call the API directly
and re-yield every 15 s — no data loader cache, no manual cache clearing.

Each page shows a live status bar (● green/red · last updated time).
Offline state shows the `make api` hint inline.

index.md: add "Registered Projects" section — polls
  /progress/?event_type=milestone&limit=500 and filters for
  "Project registered with State Hub:" events; shows project name,
  domain, path, and registration timestamp.

workstreams.md: fix broken domain column — now fetches /workstreams/
  and /topics/ in parallel and joins on topic_id client-side.
  Previously the domain column showed "unknown" for all rows because
  WorkstreamRead schema doesn't include domain.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/main.py

@@ -1,6 +1,7 @@
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
 
 from api.database import engine
 from api.routers import decisions, progress, state, tasks, topics, workstreams
@@ -19,6 +20,13 @@ app = FastAPI(
     lifespan=lifespan,
 )
 
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["http://localhost:3000", "http://127.0.0.1:3000"],
+    allow_methods=["GET", "POST", "PATCH"],
+    allow_headers=["Content-Type"],
+)
+
 app.include_router(topics.router)
 app.include_router(workstreams.router)
 app.include_router(tasks.router)