List package pages

Retrieves a list of all static HTML pages (in-package data apps) within the specified package. Each page entry includes the relative path, the package name, a canonical resource URL, and the page title (extracted from the file's <title> tag, falling back to the path). Used by the Publisher SPA to surface a clickable "Pages" section on the package detail view, and by anyone who wants to discover in-package data apps programmatically without scraping the directory. Recursive depth is capped server-side to keep this cheap on large packages.