fix(server): count quota by the key actually used, and more review fixes

Found by the PR review, each with a test that failed first:
- Quota: any key header skipped it, even one the provider never reads
  (x-aws-access-key-id with OpenAI), so a request ran on the server's
  key without being counted. The check now runs after the model is
  resolved and uses usesServerCredentials. On main already.
- usesServerCredentials read the raw base URL; "/" cleans up to none, so
  an Ollama request ran on the server's key past the server-model check.
- SGLang's default 127.0.0.1:8000 only fills the settings form. Chat and
  the model list used it as a real address, so the server called its own
  machine even with private URLs blocked. Now a base URL is required.
- With a user's OpenAI key and no base URL, the SDK read the server's
  OPENAI_BASE_URL. The official endpoint is now passed. On main already.
- The Test button refused nothing on the server's keys (Ollama Cloud),
  and a 15 s timeout reported "connected, no tool call".
- The model list for Ollama without a base URL came from ollama.com while
  chat went to the server's Ollama.
- Bedrock's "Too many tokens, please wait" counted as context too long.
- On the server's keys the provider's error text stays in the server log;
  it can name the server's AWS account, role or internal hosts.
- Desktop app: the preset keys are the user's own (NEXT_AI_DRAWIO_DESKTOP),
  so Max Output Tokens can be raised and keyless models in settings work
  again. A launch that found the remembered port taken no longer replaces
  it, which hid the user's chats and settings for good.

app/api/validate-model/route.ts

@@ -2,14 +2,15 @@ import { streamText, tool } from "ai"
 import { NextResponse } from "next/server"
 import { z } from "zod"
 import { checkAccessCode } from "@/lib/access-code"
-import { getAIModel } from "@/lib/ai-providers"
+import { getAIModel, usesServerCredentials } from "@/lib/ai-providers"
 import { classifyLLMError } from "@/lib/llm-errors"
 import { allowPrivateUrls, isPrivateUrl } from "@/lib/ssrf-protection"
+import type { ProviderName } from "@/lib/types/model-config"
 
 export const runtime = "nodejs"
 
 interface ValidateRequest {
-    provider: string
+    provider: ProviderName
     apiKey: string
     baseUrl?: string
     modelId: string
@@ -93,6 +94,22 @@ export async function POST(req: Request) {
                 { status: 400 },
             )
         }
+        // The Test button checks the user's own provider. On the server's
+        // keys (Ollama Cloud without a key or URL) anyone could run any model.
+        if (
+            usesServerCredentials(provider, {
+                apiKey,
+                baseUrl,
+                awsAccessKeyId,
+                awsSecretAccessKey,
+                vertexApiKey,
+            })
+        ) {
+            return NextResponse.json(
+                { valid: false, error: "API key is required" },
+                { status: 400 },
+            )
+        }
 
         // The same model the chat would use. A client base URL makes it
         // refuse redirects to internal hosts.
@@ -130,6 +147,14 @@ export async function POST(req: Request) {
         let finishReason: string | undefined
         for await (const part of result.fullStream) {
             if (part.type === "error") throw part.error
+            // The timeout ends the stream with an abort part, not an error
+            if (part.type === "abort") {
+                const timeout = new Error(
+                    `The model did not answer within ${TEST_TIMEOUT_MS / 1000} s.`,
+                )
+                timeout.name = "TimeoutError"
+                throw timeout
+            }
             if (part.type === "tool-call") {
                 calledTool = true
                 break