fix(admin-web): break /admin/login returnTo redirect loop in dev

vite dev only proxied /api and /auth, so /admin/login hit the SPA root
layout, re-ran loadSession, got 401, and redirected back to /admin/login
with an ever-nesting returnTo. Proxy /admin/login to the backend (which
owns it before the SPA fallback) and guard redirectToLogin against
re-entering /admin/login.

Replace the only emoji-as-icon (the back-arrow on project detail) with
the Icon component (new arrow-left glyph).

Add scripts/dev-bootstrap.ts for seeding a local Silo (stub probes) so
npm run dev can start on a fresh dev DB.

hub/admin-web/vite.config.ts

@@ -8,6 +8,10 @@ export default defineConfig({
 		proxy: {
 			'/api': 'http://127.0.0.1:8788',
 			'/auth': 'http://127.0.0.1:8788',
+			// Backend owns /admin/login (registered before the SPA fallback in
+			// src/admin/static.ts). Proxy it in dev so the SPA doesn't re-render
+			// its layout on that path and 401-redirect into a returnTo loop.
+			'/admin/login': 'http://127.0.0.1:8788',
 		},
 	},
 });