extract expandHome utility, fix scan error handling scope

packages/opencode/src/util/filesystem.ts

@@ -2,6 +2,7 @@ import { chmod, mkdir, readFile, writeFile } from "fs/promises"
 import { createWriteStream, existsSync, statSync } from "fs"
 import { lookup } from "mime-types"
 import { realpathSync } from "fs"
+import os from "os"
 import { dirname, join, relative, resolve as pathResolve } from "path"
 import { Readable } from "stream"
 import { pipeline } from "stream/promises"
@@ -95,6 +96,10 @@ export namespace Filesystem {
     }
   }
 
+  export function expandHome(p: string): string {
+    return p.startsWith("~/") ? join(os.homedir(), p.slice(2)) : p
+  }
+
   export function mimeType(p: string): string {
     return lookup(p) || "application/octet-stream"
   }