Armour classes, escapes, off-hands, belts and consumables

Phase 3 of #147/#148. Six armour classes (cloth, padded cloth, leather, hardened leather, chainmail, plate) on Head, Body, Feet, Hands, Arms and Legs: per-piece stats, set bonuses at 3 and 6 pieces, weight on escapes (docs/builds.md § 7). Head D, Body R and Feet F abilities chosen by design in any class; the twelve escapes and their counters (§ 8: Rooted, Silenced, Stunned, Insight; Break Free under a stun). Ten off-hands (deterministic: the Buckler blocks every 3rd frontal blow), six belts, potions, flasks, food. Key presets Albion and Classic (§ 3.3).

Done when a full kit of six ability keys plus consumables works in any armour class and both presets, and every escape kind is stopped by its counter in a test.