e55d7df1

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Deduplicate pages by canonical URL for title/description checks

When multiple URLs redirect to the same page (e.g. auth-required
account pages all redirecting to /auth/login), seocheck stores each
as a separate result keyed by the original request URL. Since they
all render the same login page, the duplicate title/description
check flags them as violations.

Fix: use the canonical URL (from <link rel="canonical">) as the
page identity when checking for duplicates. Pages that share the
same canonical URL are the same page and should not be counted as
separate entries.