v1.2.9 — Type-aware withdrawal window (digital = order date, physical = delivery)

Refines the (informational) 14-day countdown without changing the safe default behaviour.

NormalizedOrder::window_start() is now product-type-aware:

• All-digital orders (every item virtual/downloadable) → the clock starts at the order date (paid → created), the conclusion of the contract (Art. 9 Dir. 2011/83/EU — Art. 52 Cod. Consumo), no longer deferred to a later completed date.
• Everything else (any tangible item, mixed cart, unknown/empty contents) → unchanged: completed → paid → created.

Still informational only — the button is never hidden on this value (hiding on an uncertain delivery date is itself a compliance risk under Art. 11a); integrators with a real delivery date can refine via wwu_wb_compute_deadline. New conservative helper is_all_digital(). 6 new window smoke assertions, verified standalone. PHP lint clean.