release-20261029014547

Published from the staging-tested draft for commit cdb85eb.

Analytics

• /track events now go to the shared Mixpanel project 3373228 (PR #939).
• Event names are snake_case (app_opened, diagram_save_clicked, diagram_downloaded, …), every event carries product_type=web-sequence, and signed-out users get an anonymous distinct_id. Old Chrome extension builds are mapped to the new names on the server (PR #940).

Internal: one previewRpc client for export rendering (PR #898); removed one-off web scripts and committed review screenshots (PR #893).