Mathlib ₀ rename (2026-09): Finset.prod_le_one/one_le_prod now mean the monoid version

Mathlib PR #39692 (deprecations dated 2026-09-01; present in v4.35.0 and v4.36.0-rc2) renamed the ordered-semiring product lemmas with a ₀ suffix: prod_le_prod₀, prod_le_one₀, one_le_prod₀, prod_le_prod_of_subset_of_one_le₀, prod_le_prod_of_subset_of_le_one₀, prod_mono_set_of_one_le₀, prod_anti_set_of_le_one₀, prod_le_prod_of_injOn₀, prod_lt_prod₀, prod_lt_prod_of_nonempty₀. It also dropped the prime from the ordered-monoid versions, which now occupy the plain names: prod_le_prod', one_le_prod', prod_le_one' and single_le_prod' are deprecated aliases that warn. Because the plain names were reused, old semiring calls get no deprecation hint. Finset.prod_le_one h0 h1 on ℝ fails with 'Function expected at prod_le_one ?m', and Finset.one_le_prod h on ℝ fails with 'failed to synthesize MulLeftMono ℝ'; add ₀ to fix both. Separately, sum_nonneg' and one_le_prod'' (global hypothesis ∀ i, 0 ≤ f i) are deprecated with +typeChanged. They still compile with a warning, but the suggested sum_nonneg takes ∀ i ∈ s, so write sum_nonneg fun i _ => hf i.