Archive the Free and Teams Polar products in production #1000

Question

Parent map: #973. Decided in #977: one purchasable plan at launch, Free and Teams dropped, no signup-time free subscription.

Archive the retired Polar products in production so the live tree matches the decision:

• Archive the Free product and the Teams product in the Polar production dashboard.
• Cancel or revoke every remaining subscription on those products (the $0 free subscriptions created at signup).
• Remove POLAR_PRODUCT_FREE_ID, POLAR_PRODUCT_TEAMS_ID, and the HOBBY/PRO alias variables from the Railway environment.
• Name the one remaining paid product "Pro", priced $9/month recurring (Which plans Cloud sells at 0.2.0).
• Confirm the nightly reconcile runs clean after the code from Make Cloud config and billing optional for self-hosters #994 lands (no unknown-product subscriptions listed).

Record here: which product IDs were archived, how many subscriptions were cancelled, and the remaining paid product ID.