docs: document intentional design decisions in atlas, todo-continuation, and delegation hooks

src/hooks/atlas/sisyphus-path.ts

@@ -1,6 +1,7 @@
 /**
  * Cross-platform check if a path is inside .sisyphus/ directory.
  * Handles both forward slashes (Unix) and backslashes (Windows).
+ * Uses path segment matching (not substring) to avoid false positives like "not-sisyphus/file.txt"
  */
 export function isSisyphusPath(filePath: string): boolean {
   return /\.sisyphus[/\\]/.test(filePath)