feat(headroom): add proxy lifecycle management + dashboard UI

Build on the optional Headroom Token Saver from Carmelo Campos
(PR: feat: add optional Headroom token saver). Add managed start/stop
of the local headroom proxy from the dashboard, install detection,
status probing, and a simplified Token Saver UI.

- detect headroom CLI + python>=3.10, probe proxy /health
- spawn/stop proxy as a detached, pid-tracked process
- /api/headroom/{status,start,stop} routes, gated local-only in dashboardGuard
- one-click Start/Stop Headroom modal, no manual config needed
- claude<->openai shape conversion for /v1/compress via 9router translators

Thanks to Carmelo Campos (@carmelogunsroses) for the original Headroom integration.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/api/headroom/start/route.js

@@ -0,0 +1,27 @@
+import { NextResponse } from "next/server";
+import { getSettings } from "@/lib/localDb";
+import { startHeadroomProxy } from "@/lib/headroom/process";
+
+export const dynamic = "force-dynamic";
+
+function parsePortFromUrl(url) {
+  try {
+    const u = new URL(url);
+    const p = parseInt(u.port, 10);
+    if (p > 0 && p < 65536) return p;
+  } catch { /* ignore, fall through to default */ }
+  return null;
+}
+
+export async function POST() {
+  try {
+    const settings = await getSettings();
+    const url = settings.headroomUrl || "http://localhost:8787";
+    const port = parsePortFromUrl(url) || 8787;
+    const result = await startHeadroomProxy({ port });
+    return NextResponse.json({ success: true, ...result });
+  } catch (error) {
+    const status = error.code === "NOT_INSTALLED" ? 400 : 500;
+    return NextResponse.json({ error: error.message, code: error.code || null }, { status });
+  }
+}

src/app/api/headroom/status/route.js

@@ -0,0 +1,18 @@
+import { NextResponse } from "next/server";
+import { getSettings } from "@/lib/localDb";
+import { getHeadroomStatus } from "@/lib/headroom/detect";
+import { getManagedPid } from "@/lib/headroom/process";
+
+export const dynamic = "force-dynamic";
+
+export async function GET() {
+  try {
+    const settings = await getSettings();
+    const url = settings.headroomUrl || "http://localhost:8787";
+    const status = await getHeadroomStatus(url);
+    const managedPid = getManagedPid();
+    return NextResponse.json({ ...status, url, managedPid });
+  } catch (error) {
+    return NextResponse.json({ error: error.message }, { status: 500 });
+  }
+}

src/app/api/headroom/stop/route.js

@@ -0,0 +1,14 @@
+import { NextResponse } from "next/server";
+import { stopHeadroomProxy } from "@/lib/headroom/process";
+
+export const dynamic = "force-dynamic";
+
+export async function POST() {
+  try {
+    const result = stopHeadroomProxy();
+    const status = result.stopped ? 200 : 409;
+    return NextResponse.json({ ...result }, { status });
+  } catch (error) {
+    return NextResponse.json({ error: error.message, code: error.code || null }, { status: 500 });
+  }
+}