Consolidates the scattered per-analyst pages into /me/activity (usage
analytics) and /me/profile (account hub). /me/stats and /profile/sessions
301-redirect; /profile, /me/debug, /tokens are removed with every internal
link repointed. Includes an XSS fix in the /me/activity page hero, the
user_id-keyed session-lookup alignment, and the v0.54.15 release cut.
Co-developed by @ZdenekSrotyr and @cvrysanek.