crafting: actor-precondition (requires) + reward (grants) — Skills half of Phase H (ADR-0056)

lib-core.crafting v0.4.0: two optional domain-free recipe fields.
- `requires`: a match-table evaluated against ctx.actor (not container items) — a hard gate. Failing -> {ok=false, error="requires_unmet", unmet={keys}}; fail-closed when ctx.actor is nil. Same predicate machinery as slots; distinct from is_known (discovery vs lock).
- `grants`: property->number reward, returned as `granted` from craft(); the consuming MODULE applies it to the actor (crafting stays container-scoped). Crafting knows no 'skill' vocabulary (ADR-0001).

vagrant-skeleton v0.21.0: player-actor carries skill.knapping (entity property, Phase-A lesson); knap_sharp_stone grants knapping XP, craft_stone_axe requires knapping>=3; module applies granted; skill-locked recipes show 'Skill too low'. Gate->earn->unlock loop headless-verified (axe locked @0 requires_unmet -> 3 knaps -> unlocks).

Quality-band reserved (Phase J): the requires threshold = the future quality floor (no re-authoring). Docs synced: ADR-0056, crafting-model.md (v0.4.0 + Actor-Precondition section), libraries.md, crafting README, vagrant README.

content/stone_age.lua

@@ -21,6 +21,12 @@
 -- `inputs` and non-consumed `tools`; the inputs/tools split (not a separate
 -- axis) says whether the item is used up.
 --
+-- ACTOR-SIDE (crafting v0.4 / ADR-0056): a recipe may also gate on / reward the
+-- ACTOR, not the ingredients:
+--   * `requires = { ["skill.knapping"]=">=3" }` — hard gate vs ctx.actor
+--   * `grants   = { ["skill.knapping"]=1 }`     — XP given on successful craft
+-- Same predicate machine; the module applies `grants` to the actor.
+--
 -- `form` was RETIRED (ADR-0055 amendment): a physical-shape axis mixed
 -- geometry, identity and capability. Its functional members became
 -- affordances; its identity members (a "tree") stay template-id.
@@ -86,10 +92,13 @@ return function(c)
     -- ---- recipes (match by CAPABILITY, not by item id) --------------
     -- knap: any KNAPPABLE stone + a HAMMERING tool -> a cutting edge.
     -- (rock is knappable; sharp_stone is NOT → no self-recursion.)
+    -- Skill-ungated but GRANTS knapping XP (ADR-0056) — the accessible "grind"
+    -- recipe that bootstraps the gated craft_stone_axe below.
     c.R{ id = "knap_sharp_stone",
          inputs  = { { match = { ["affordance.knappable"] = true }, count = 1 } },
          tools   = { { match = { ["affordance.hammering"] = true } } },
          outputs = { { template = "sharp_stone", count = 1 } },
+         grants  = { ["skill.knapping"] = 1 },
          name = "Knap Sharp Stone",
          description = "Strike a stone with a hammerstone to flake off a sharp edge." }
 
@@ -115,15 +124,18 @@ return function(c)
          description = "Lash a stone to a haft for a pounding tool (enables knapping)." }
 
     -- axe: a CUTTING head + a LEVERAGE haft + a BINDING.
+    -- Skill-GATED (ADR-0056): needs knapping >=3, earned by knap_sharp_stone.
+    -- Demonstrates the gate+earn+unlock loop (gate downstream, grant upstream).
     c.R{ id = "craft_stone_axe",
          inputs = {
              { match = { ["affordance.cutting"]  = true }, count = 1 },  -- head (a sharp stone)
              { match = { ["affordance.leverage"] = true }, count = 1 },  -- haft
              { match = { ["affordance.binding"]  = true }, count = 1 },  -- binding
          },
-         outputs = { { template = "stone_axe", count = 1 } },
+         requires = { ["skill.knapping"] = ">=3" },
+         outputs  = { { template = "stone_axe", count = 1 } },
          name = "Haft Stone Axe",
-         description = "Bind a sharp stone to a haft with cordage." }
+         description = "Bind a sharp stone to a haft with cordage. (Needs knapping skill 3.)" }
 
     -- break: a HEAVY leverage-thing (branch, not a light stick) -> two sticks.
     c.R{ id = "break_branch",