Route all AI features through the Switchboard gateway

Replace the direct Anthropic and OpenAI integrations with a single
provider that talks to Switchboard, an OpenAI-compatible gateway that
routes each request to the best available model. The app no longer pins
a model id anywhere: it sends switchboard/auto and lets the gateway
choose, then logs which model answered and what it cost.

Routing levers are set per feature in src/lib/ai/routing.ts. Three of
those choices came from measuring against the live gateway:

- category and prefer_free are set explicitly on every request. An API
  key carries its own routing defaults, and anything left unset inherits
  them - drink prompts were being sent to a free coding model.
- Token budgets are generous because the router may pick a reasoning
  model, and reasoning tokens come out of the same max_tokens budget as
  the answer. At 512 tokens a request returned null content; at 4096 the
  same request returned correct JSON.
- No tier lever on text features. tier "cheap" pinned a slow reasoning
  model (42-180s, two timeouts and one truncated response in five
  trials) and tier "frontier" escalated as far as Opus at $0.02 a call,
  while unconstrained routing answered in about a second. Vision keeps
  "frontier", where the accuracy is worth a few tenths of a cent.

Gateway failures are mapped to actionable messages rather than passed
through: a 401 relayed as 401 would read as an expired session and
bounce the user to login, and a 429 would collide with the app's own
rate limiter.

Also collapses the key lookup that was duplicated across ten call sites
into getUserProvider(), which fixes a latent bug where a bare findFirst
with no ordering let different features pick different providers.

Existing claude/openai key rows are ignored at runtime and offered for
removal in Settings, so no migration is needed before deploying.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/app/(app)/settings/page.tsx

@@ -20,11 +20,16 @@ interface ApiKeyInfo {
   isActive: boolean
 }
 
+interface ApiKeysResponse {
+  keys: ApiKeyInfo[]
+  gatewayUrl: string
+}
+
 export default function SettingsPage() {
   const queryClient = useQueryClient()
 
   // API Keys
-  const { data: apiKeys = [] } = useQuery<ApiKeyInfo[]>({
+  const { data: apiKeyData } = useQuery<ApiKeysResponse>({
     queryKey: ["api-keys"],
     queryFn: async () => {
       const res = await fetch("/api/settings/api-keys")
@@ -33,6 +38,11 @@ export default function SettingsPage() {
     },
   })
 
+  const apiKeys = apiKeyData?.keys ?? []
+  const legacyKeys = apiKeys.filter(
+    (k) => k.provider === "claude" || k.provider === "openai"
+  )
+
   // Preferences
   const { data: preferences, isLoading: prefsLoading } = useQuery({
     queryKey: ["preferences"],
@@ -74,16 +84,32 @@ export default function SettingsPage() {
           <CardHeader>
             <CardTitle className="flex items-center gap-2">
               <Key className="h-5 w-5" />
-              AI Provider Keys
+              AI Gateway
             </CardTitle>
             <CardDescription>
-              Add your API keys for AI-powered menu scanning. Keys are encrypted and stored securely.
+              AI features route through Switchboard, which picks the best model for each
+              request. Add your gateway API key below — it is encrypted before storage.
+              {apiKeyData?.gatewayUrl && (
+                <>
+                  {" "}
+                  This app is pointed at{" "}
+                  <code className="text-xs">{apiKeyData.gatewayUrl}</code>.
+                </>
+              )}
             </CardDescription>
           </CardHeader>
           <CardContent className="space-y-4">
-            <ApiKeyForm provider="claude" label="Anthropic Claude" existingKey={apiKeys.find(k => k.provider === "claude")} />
-            <Separator />
-            <ApiKeyForm provider="openai" label="OpenAI GPT-4o" existingKey={apiKeys.find(k => k.provider === "openai")} />
+            <ApiKeyForm
+              provider="switchboard"
+              label="Switchboard Gateway"
+              existingKey={apiKeys.find((k) => k.provider === "switchboard")}
+            />
+            {legacyKeys.length > 0 && (
+              <>
+                <Separator />
+                <LegacyKeyNotice keys={legacyKeys} />
+              </>
+            )}
           </CardContent>
         </Card>
 
@@ -115,6 +141,62 @@ export default function SettingsPage() {
   )
 }
 
+const LEGACY_PROVIDER_LABELS: Record<string, string> = {
+  claude: "Anthropic Claude",
+  openai: "OpenAI",
+}
+
+/**
+ * Keys left over from when the app called Claude and OpenAI directly. They are
+ * already ignored when picking a provider, but they are shown here so a user who
+ * still has one can see it is inert and remove it.
+ */
+function LegacyKeyNotice({ keys }: { keys: ApiKeyInfo[] }) {
+  const queryClient = useQueryClient()
+
+  const deleteKey = useMutation({
+    mutationFn: async (provider: string) => {
+      const res = await fetch(`/api/settings/api-keys?provider=${provider}`, {
+        method: "DELETE",
+      })
+      if (!res.ok) throw new Error("Failed to delete API key")
+    },
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ["api-keys"] })
+    },
+  })
+
+  return (
+    <div className="rounded-md border border-dashed p-3 space-y-3">
+      <p className="text-sm text-muted-foreground">
+        These keys are from an earlier version that called each AI provider directly.
+        They are no longer used and can be removed.
+      </p>
+      {keys.map((key) => (
+        <div key={key.id} className="flex items-center justify-between gap-2">
+          <div>
+            <p className="text-sm font-medium">
+              {LEGACY_PROVIDER_LABELS[key.provider] ?? key.provider}
+            </p>
+            <code className="text-xs bg-muted px-2 py-0.5 rounded">
+              {key.maskedKey}
+            </code>
+          </div>
+          <Button
+            variant="outline"
+            size="sm"
+            onClick={() => deleteKey.mutate(key.provider)}
+            disabled={deleteKey.isPending}
+          >
+            <Trash2 className="h-4 w-4 mr-1 text-destructive" />
+            Remove
+          </Button>
+        </div>
+      ))}
+    </div>
+  )
+}
+
 function ApiKeyForm({
   provider,
   label,