move pi-mono into companion-cloud as apps/companion-os

- Copy all pi-mono source into apps/companion-os/
- Update Dockerfile to COPY pre-built binary instead of downloading from GitHub Releases
- Update deploy-staging.yml to build pi from source (bun compile) before Docker build
- Add apps/companion-os/** to path triggers
- No more cross-repo dispatch needed

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/ai/src/providers/github-copilot-headers.ts

@@ -0,0 +1,37 @@
+import type { Message } from "../types.js";
+
+// Copilot expects X-Initiator to indicate whether the request is user-initiated
+// or agent-initiated (e.g. follow-up after assistant/tool messages).
+export function inferCopilotInitiator(messages: Message[]): "user" | "agent" {
+  const last = messages[messages.length - 1];
+  return last && last.role !== "user" ? "agent" : "user";
+}
+
+// Copilot requires Copilot-Vision-Request header when sending images
+export function hasCopilotVisionInput(messages: Message[]): boolean {
+  return messages.some((msg) => {
+    if (msg.role === "user" && Array.isArray(msg.content)) {
+      return msg.content.some((c) => c.type === "image");
+    }
+    if (msg.role === "toolResult" && Array.isArray(msg.content)) {
+      return msg.content.some((c) => c.type === "image");
+    }
+    return false;
+  });
+}
+
+export function buildCopilotDynamicHeaders(params: {
+  messages: Message[];
+  hasImages: boolean;
+}): Record<string, string> {
+  const headers: Record<string, string> = {
+    "X-Initiator": inferCopilotInitiator(params.messages),
+    "Openai-Intent": "conversation-edits",
+  };
+
+  if (params.hasImages) {
+    headers["Copilot-Vision-Request"] = "true";
+  }
+
+  return headers;
+}