feat: integrate 5 feature branches, upstream fixes, and MIME detection fix

Squashed 5 commits:

Features (from 5 feature branches):
- MCP fix, pipe mute, stub recovery
- KAIROS activation, openclaw autonomy
- Daemon/job command hierarchy + cross-platform bg engine

Upstream fixes:
- fix: Bun.hash compatibility
- chore: chrome dependency update
- docs: browser support guide

MIME detection fix:
- Screenshot detectMimeFromBase64(): decode raw bytes from base64
  instead of broken charCodeAt comparison
- Fixes API 400 on Windows (JPEG) and macOS (PNG) screenshots

packages/@ant/computer-use-mcp/src/toolCalls.ts

@@ -37,16 +37,21 @@
 import type { CallToolResult } from "@modelcontextprotocol/sdk/types.js";
 import { randomUUID } from "node:crypto";
 
-/** Detect actual image MIME type from base64 data using magic bytes. */
+/** Detect actual image MIME type from base64 data by decoding the magic bytes. */
 function detectMimeFromBase64(b64: string): string {
-  // First byte is enough to distinguish PNG (0x89) from JPEG (0xFF)
-  const c = b64.charCodeAt(0);
-  if (c === 0x89) return "image/png";
-  if (c === 0xFF) return "image/jpeg";
-  // RIFF = WebP
-  if (c === 0x52) return "image/webp";
-  // GIF
-  if (c === 0x47) return "image/gif";
+  // Decode first 12 raw bytes (16 base64 chars is enough) and check standard magic bytes.
+  // PNG:  89 50 4E 47
+  // JPEG: FF D8 FF
+  // RIFF+WEBP: "RIFF" at 0..3 + "WEBP" at 8..11
+  // GIF:  "GIF" at 0..2
+  const raw = Buffer.from(b64.slice(0, 16), "base64");
+  if (raw[0] === 0x89 && raw[1] === 0x50 && raw[2] === 0x4e && raw[3] === 0x47) return "image/png";
+  if (raw[0] === 0xff && raw[1] === 0xd8 && raw[2] === 0xff) return "image/jpeg";
+  if (
+    raw[0] === 0x52 && raw[1] === 0x49 && raw[2] === 0x46 && raw[3] === 0x46 && // RIFF
+    raw[8] === 0x57 && raw[9] === 0x45 && raw[10] === 0x42 && raw[11] === 0x50  // WEBP
+  ) return "image/webp";
+  if (raw[0] === 0x47 && raw[1] === 0x49 && raw[2] === 0x46) return "image/gif";
   return "image/png";
 }