Replace catch-all proxy with dedicated routes, add 404 page

- Dedicated proxy routes for sessions, messages, search, memory, config
- Removes [...path] catch-all that conflicted with specific routes
- Session detail + delete proxy
- Custom 404 page matching design system

app/api/sessions/[id]/messages/route.ts

@@ -0,0 +1,18 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const BACKEND = process.env.HERMES_BACKEND_URL || "http://127.0.0.1:8643";
+
+export async function GET(req: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  const qs = req.nextUrl.search;
+  try {
+    const res = await fetch(BACKEND + "/api/sessions/" + id + "/messages" + qs);
+    const data = await res.text();
+    return new NextResponse(data, {
+      status: res.status,
+      headers: { "content-type": "application/json" },
+    });
+  } catch {
+    return NextResponse.json({ items: [], total: 0 }, { status: 502 });
+  }
+}

app/api/sessions/[id]/route.ts

@@ -0,0 +1,31 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const BACKEND = process.env.HERMES_BACKEND_URL || "http://127.0.0.1:8643";
+
+export async function GET(_req: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(BACKEND + "/api/sessions/" + id);
+    const data = await res.text();
+    return new NextResponse(data, {
+      status: res.status,
+      headers: { "content-type": "application/json" },
+    });
+  } catch {
+    return NextResponse.json({ error: "backend unreachable" }, { status: 502 });
+  }
+}
+
+export async function DELETE(_req: NextRequest, { params }: { params: Promise<{ id: string }> }) {
+  const { id } = await params;
+  try {
+    const res = await fetch(BACKEND + "/api/sessions/" + id, { method: "DELETE" });
+    const data = await res.text();
+    return new NextResponse(data, {
+      status: res.status,
+      headers: { "content-type": "application/json" },
+    });
+  } catch {
+    return NextResponse.json({ error: "backend unreachable" }, { status: 502 });
+  }
+}