feat: add companion API and Android APK shell

apps/companion/src/config/paths.ts

@@ -0,0 +1,27 @@
+import { isAbsolute, relative, resolve, sep } from 'node:path';
+
+const ignoredPathSegments = new Set(['.git', '.dev', 'node_modules', 'dist', 'android']);
+
+export function toSafeAbsolutePath(workspaceRoot: string, requestedPath = '.'): string {
+  const root = resolve(workspaceRoot);
+  const target = resolve(root, requestedPath || '.');
+  const relativePath = relative(root, target);
+
+  if (relativePath === '' || (!relativePath.startsWith('..') && !relativePath.includes(`..${sep}`) && !isAbsolute(relativePath))) {
+    return target;
+  }
+
+  throw new Error('Path is outside the configured workspace root');
+}
+
+export function toWorkspacePath(workspaceRoot: string, absolutePath: string): string {
+  const relativePath = relative(resolve(workspaceRoot), resolve(absolutePath));
+  return relativePath === '' ? '.' : relativePath.split(sep).join('/');
+}
+
+export function isIgnoredWorkspacePath(workspacePath: string): boolean {
+  return workspacePath
+    .split('/')
+    .filter(Boolean)
+    .some((segment) => ignoredPathSegments.has(segment));
+}