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

tests/mocks/file-system.ts

@@ -1,15 +1,13 @@
-import { mkdtemp, rm, writeFile, mkdir } from "node:fs/promises";
-import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { mkdtemp, rm, writeFile, mkdir } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { dirname, join } from 'node:path'
 
-export async function createTempDir(
-  prefix = "claude-test-",
-): Promise<string> {
-  return mkdtemp(join(tmpdir(), prefix));
+export async function createTempDir(prefix = 'claude-test-'): Promise<string> {
+  return mkdtemp(join(tmpdir(), prefix))
 }
 
 export async function cleanupTempDir(dir: string): Promise<void> {
-  await rm(dir, { recursive: true, force: true });
+  await rm(dir, { recursive: true, force: true })
 }
 
 export async function writeTempFile(
@@ -17,16 +15,18 @@ export async function writeTempFile(
   name: string,
   content: string,
 ): Promise<string> {
-  const path = join(dir, name);
-  await writeFile(path, content, "utf-8");
-  return path;
+  const path = join(dir, name)
+  const parentDir = dirname(path)
+  await mkdir(parentDir, { recursive: true })
+  await writeFile(path, content, 'utf-8')
+  return path
 }
 
 export async function createTempSubdir(
   dir: string,
   name: string,
 ): Promise<string> {
-  const path = join(dir, name);
-  await mkdir(path, { recursive: true });
-  return path;
+  const path = join(dir, name)
+  await mkdir(path, { recursive: true })
+  return path
 }