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/ai-providers.ts

@@ -25,6 +25,7 @@ import { getEnvFallback } from "@/lib/admin/settings"
 import { isPrivateUrl, redirectGuardedFetch } from "@/lib/ssrf-protection"
 import {
     normalizeBaseUrl,
+    ollamaApiUrl,
     PROVIDER_INFO,
     type ProviderName,
 } from "@/lib/types/model-config"
@@ -1025,7 +1026,7 @@ export function getAIModel(clientOverrides?: ClientOverrides): ModelConfig {
                     ? PROVIDER_INFO.ollama.defaultBaseUrl
                     : resolveBaseUrlEnv(overrides, "OLLAMA_BASE_URL"))
             model = createOllama({
-                ...(baseURL && { baseURL }),
+                ...(baseURL && { baseURL: ollamaApiUrl(baseURL) }),
                 ...(apiKey && {
                     headers: { Authorization: `Bearer ${apiKey}` },
                 }),