feat(favicon): serve project favicon reusing the header envelope logo

Serve an inline SVG icon at /favicon.svg and /favicon.ico and link it
from the shared Layout and the standalone entry view, so the admin UI,
status page, and entry pages stop emitting /favicon.ico 404s. Doubles
as the fallback for the upcoming per-feed favicon feature.

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

src/index.ts

@@ -8,6 +8,7 @@ import { handle as handleEntry } from "./routes/entries";
 import { handle as handleFiles } from "./routes/files";
 import { handle as handleStats } from "./routes/stats";
 import { handle as handleHome } from "./routes/home";
+import { handle as handleFavicon } from "./routes/favicon";
 import { hubRouter } from "./routes/hub";
 import { handleCloudflareEmail } from "./lib/cloudflare-email";
 import { Env } from "./types";
@@ -168,6 +169,10 @@ app.route("/files", files);
 app.route("/admin", admin);
 app.route("/hub", hubRouter);
 
+// Project favicon (also the fallback for the future per-feed favicon)
+app.get("/favicon.svg", handleFavicon);
+app.get("/favicon.ico", handleFavicon); // readers/browsers that hardcode .ico
+
 // Health check endpoint for monitoring
 app.get("/health", (c) => c.json({ status: "ok", timestamp: Date.now() }));