Theseus: translator talks to silentmode.st/libre + libre.x / lingua.x

The translator client now ships with the right defaults for the actual
deployment: silentmode.st/libre (ICANN, via the main cert and no new
subdomain) is the primary peer; libre.x and lingua.x are registered on
BNS with `p` records that reverse-proxy back to the same backend; the
public LibreTranslate.com key-gated tier stays as the last-resort entry.

Two wiring fixes make the BNS fallback actually usable from Theseus:

1. translatorPostOnce rewrites the request URL through targetUrlFor
   before fetching, so a peer whose host is a BNS name (libre.x) is
   dispatched via the in-process bns:// handler — Chromium's net stack
   has no way to resolve `.x` by itself.

2. serveBns's p-record branch now forwards the method, headers and body
   of the original request to the upstream, not just a GET. Without
   that, a POST /translate against libre.x arrived at the backend as
   a GET with no body and 400'd — now the proxy is actually a reverse-
   proxy, as the record type's name promises.

Verified end-to-end against the live silentmode.st/libre instance from a
fresh Theseus profile with a Spanish test page: both the direct
silentmode.st/libre peer and the libre.x -> bns:// -> serveP -> upstream
path translate the page and the revert path restores the originals.

main.js

@@ -529,13 +529,15 @@ const SETTINGS_DEFAULTS = {
   // (the libretranslate.com free tier moved behind an API key in late
   // 2026, several mirrors 502 at any given time), so a list beats one
   // endpoint: a dead mirror doesn't kill the feature, it just loses the
-  // round. Silent Mode's own instances come first: libre.silentmode.st
+  // round. Silent Mode's own instances come first: silentmode.st/libre
-  // under ICANN and libre.x on BNS (lingua.x is registered as an alias
+  // under ICANN (served as a sub-path to re-use the main cert instead
-  // of libre.x — same ip record, same backend — so it's a resolution
+  // of standing up a subdomain + separate TLS) and libre.x on BNS
-  // convenience, not another independent peer). Users can edit the list
+  // (lingua.x is registered as an alias of libre.x — same ip record,
-  // in Settings › General › Translate pages.
+  // same backend — so it's a resolution convenience, not another
+  // independent peer). Users can edit the list in Settings › General
+  // › Translate pages.
   translateEndpoints: [
-    "https://libre.silentmode.st/translate",
+    "https://silentmode.st/libre/translate",
     "https://libre.x/translate",
     "https://libretranslate.com/translate",
   ],
@@ -1983,8 +1985,25 @@ async function serveBns(request) {
     const base = new URL(r.p);
     const prefix = base.pathname === "/" ? "" : base.pathname.replace(/\/$/, "");
     const target = base.origin + prefix + rawPath + url.search;
+    // Forward method + headers + body: a p-record is a reverse-proxy, so an
+    // API behind it (POST /translate, PUT, …) needs the live request as the
+    // caller sent it, not a bare GET. Hop-by-hop and host-rewriting headers
+    // are stripped — the upstream is a different origin and sees its own
+    // Host.
+    const method = request.method || "GET";
+    const headers = {};
+    const SKIP = new Set(["host", "connection", "content-length", "transfer-encoding", "accept-encoding"]);
+    try {
+      for (const [k, v] of request.headers.entries()) {
+        if (!SKIP.has(k.toLowerCase())) headers[k] = v;
+      }
+    } catch {}
+    const init = { method, headers, redirect: "manual" };
+    if (method !== "GET" && method !== "HEAD" && request.body) {
+      try { init.body = Buffer.from(await request.arrayBuffer()); } catch {}
+    }
     // contentFetch so Tor covers this too (a plain fetch leaked the real IP).
-    const up = await contentFetch(target, { redirect: "manual" });
+    const up = await contentFetch(target, init);
     return upstreamResponse(up, up.contentType || guessType(reqPath));
   };
   try {
@@ -4579,11 +4598,16 @@ async function translatorPostOnce(url, texts, from, to) {
     format: "text",
   };
   if (settings.translateApiKey) body.api_key = settings.translateApiKey;
+  // A peer whose host is a BNS name (libre.x, lingua.x, …) can't be reached
+  // by Chromium's net stack directly — those names aren't in ICANN DNS. Rewrite
+  // the request URL to bns:// so the in-process serveBns handler resolves the
+  // name (p-record = reverse-proxy to the upstream + path concatenation).
+  const target = (await targetUrlFor(url)) || url;
   // session.defaultSession.fetch goes through Electron's own network stack,
   // so Tor (session proxy) and any add-on proxy settings apply the same way
   // they do for a tab's fetch; Node's global fetch would bypass both.
   const sfetch = (session.defaultSession.fetch || fetch).bind(session.defaultSession);
-  const r = await sfetch(url, {
+  const r = await sfetch(target, {
     method: "POST",
     headers: { "content-type": "application/json" },
     body: JSON.stringify(body),