feat(web): SPA shell — gate, settings, today placeholder

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/src/pages/Settings.tsx

@@ -0,0 +1,50 @@
+import { useEffect, useState } from "react";
+import type { SettingsResponse } from "@helios/shared";
+import { api } from "../api";
+
+export function Settings() {
+  const [current, setCurrent] = useState<SettingsResponse | null>(null);
+  const [llmBaseUrl, setLlmBaseUrl] = useState("");
+  const [llmModel, setLlmModel] = useState("");
+  const [llmKey, setLlmKey] = useState("");
+  const [status, setStatus] = useState<string | null>(null);
+
+  useEffect(() => {
+    api.getSettings().then((s) => {
+      setCurrent(s);
+      setLlmBaseUrl(s.llmBaseUrl);
+      setLlmModel(s.llmModel);
+    });
+  }, []);
+
+  const save = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setStatus(null);
+    try {
+      await api.putSettings({ llmBaseUrl, llmModel, ...(llmKey ? { llmKey } : {}) });
+      setLlmKey("");
+      setCurrent(await api.getSettings());
+      setStatus("Saved");
+    } catch (err) {
+      setStatus(err instanceof Error ? err.message : "failed");
+    }
+  };
+
+  if (!current) return <p>Loading…</p>;
+  return (
+    <section>
+      <h2>AI provider</h2>
+      <p>Any OpenAI-compatible endpoint. OpenRouter by default; point at Ollama for a fully local setup.</p>
+      <form onSubmit={save}>
+        <label>Base URL <input value={llmBaseUrl} onChange={(e) => setLlmBaseUrl(e.target.value)} /></label>
+        <label>Model <input value={llmModel} onChange={(e) => setLlmModel(e.target.value)} /></label>
+        <label>
+          API key{current.llmKeyMasked ? ` (saved: ${current.llmKeyMasked})` : ""}
+          <input type="password" value={llmKey} onChange={(e) => setLlmKey(e.target.value)} placeholder="paste to replace" />
+        </label>
+        <button type="submit">Save</button>
+      </form>
+      {status && <p>{status}</p>}
+    </section>
+  );
+}