fix(ollama): send chat requests to the /api path

The Ollama SDK appends /chat to the base URL, and Ollama serves chat at
/api/chat. The model list already added the missing /api, so with
"http://localhost:11434" (the address our docs showed) models were listed
but every chat request went to /chat and got a 404. An OpenAI-style
".../v1" address went to /v1/chat.

ollamaApiUrl() turns the server address, ".../v1" and ".../api" into
".../api". Chat, the model list and the settings dialog's request URL
hint all use it. The docs now show http://localhost:11434/api, which also
works on released versions.

lib/provider-models.ts

@@ -3,6 +3,7 @@ import { getModelInfo } from "@/lib/model-catalog"
 import { readLimitedBody } from "@/lib/read-limited-body"
 import {
     normalizeBaseUrl,
+    ollamaApiUrl,
     PROVIDER_INFO,
     type ProviderName,
 } from "@/lib/types/model-config"
@@ -200,8 +201,11 @@ export async function listProviderModels(
             break
         }
         case "ollama": {
-            const api = base.endsWith("/api") ? base : `${base}/api`
-            const data = await getJson(`${api}/tags`, bearer, fetchFn)
+            const data = await getJson(
+                `${ollamaApiUrl(base)}/tags`,
+                bearer,
+                fetchFn,
+            )
             models = (data.models ?? []).map((m: { name: string }) => ({
                 id: m.name,
             }))