CookieJar stored cookies as domain -> name -> entry, so a second
Set-Cookie with the same name but a different path silently overwrote the
first (RFC 6265 §5.3 identifies a cookie by name+domain+path). The
retrieval side already treated path as part of identity — get_cookie_header
path-matches, and delete_cookies_filtered keys on (name, path) — so only
storage lost cookies.
Rekey the inner map by (name, path). A Max-Age=0 / expired Set-Cookie now
deletes exactly the (name, path) it targets instead of every same-name
cookie; delete_cookie(name) still clears all paths (retain by entry name).
Adds tests: same-name/different-path coexistence and no cross-path leak,
same-name/same-path replacement, and path-scoped deletion leaving a
sibling-path cookie intact.
Andrey Mnatsakanov
c8e482fde9