Merge remote-tracking branch 'origin/master' into gitea/feature/end

Resolved conflicts taking origin/master (v0.5.55) as canonical, with local
features re-applied:
- runtime log level (LOG_LEVEL env + dashboard Settings → Logging, applied
  immediately and persisted across restarts)
- free/noAuth provider enable/disable toggle via providerStrategies.enabled
- parallel model testing (Test All Models / Test Selected Keys)

tests/unit/custom-server-h2c.test.cjs

@@ -0,0 +1,65 @@
+const assert = require("node:assert/strict");
+const http = require("node:http");
+const net = require("node:net");
+const test = require("node:test");
+
+test("serves h2c POST requests as HTTP/1.1", async () => {
+  const originalCreateServer = http.createServer;
+  delete require.cache[require.resolve("../../custom-server.js")];
+  require("../../custom-server.js");
+
+  const server = http.createServer(async (req, res) => {
+    assert.equal(req.url, "/v1/chat/completions");
+    assert.equal(req.headers.upgrade, undefined);
+    assert.equal(req.headers["http2-settings"], undefined);
+    assert.equal(req.headers.connection, "close");
+    const body = [];
+    for await (const chunk of req) body.push(chunk);
+    assert.equal(Buffer.concat(body).toString("utf8"), '{"model":"test","stream":true}');
+    res.setHeader("Content-Type", "text/event-stream");
+    res.end("data: [DONE]\n\n");
+  });
+  server.on("upgrade", (_req, socket) => socket.destroy());
+
+  try {
+    await new Promise((resolve, reject) => {
+      server.once("error", reject);
+      server.listen(0, "127.0.0.1", resolve);
+    });
+    const port = server.address().port;
+
+    const response = await new Promise((resolve, reject) => {
+      const chunks = [];
+      const socket = net.createConnection({ host: "127.0.0.1", port }, () => {
+        const body = '{"model":"test","stream":true}';
+        socket.write([
+          "POST /v1/chat/completions HTTP/1.1",
+          `Host: 127.0.0.1:${port}`,
+          "Connection: Upgrade, HTTP2-Settings",
+          "Upgrade: h2c",
+          "HTTP2-Settings: AAEAAEAAAAIAAAAAAAMAAAAAAAQBAAAAAAUAAEAAAAYABgAA",
+          `Content-Length: ${Buffer.byteLength(body)}`,
+          "Content-Type: application/json",
+          "",
+          "",
+        ].join("\r\n"));
+        setImmediate(() => socket.write(body));
+      });
+      socket.setTimeout(2_000, () => {
+        socket.destroy();
+        reject(new Error("h2c fallback response timed out"));
+      });
+      socket.on("data", (chunk) => chunks.push(chunk));
+      socket.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")));
+      socket.on("error", reject);
+    });
+
+    assert.match(response, /^HTTP\/1\.1 200 OK\r\n/);
+    assert.match(response, /\r\nContent-Type: text\/event-stream\r\n/i);
+    assert.match(response, /\r\nConnection: close\r\n/i);
+    assert.match(response, /\r\n\r\ndata: \[DONE\]\n\n$/);
+  } finally {
+    await new Promise((resolve) => server.close(resolve));
+    http.createServer = originalCreateServer;
+  }
+});