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.

manifest.module

@@ -1,6 +1,6 @@
 {
     "id": "vagrant-skeleton",
-    "version": "0.20.0",
+    "version": "0.21.0",
     "kind": "module",
     "api": "^0.1",
     "ci_frames": 60,
@@ -26,7 +26,7 @@
         {"id": "lib-core.puppet",                 "version": "0.5.0"},
         {"id": "lib-core.interaction",            "version": "0.1.0"},
         {"id": "lib-core.inventory-list",         "version": "0.1.0"},
-        {"id": "lib-core.crafting",               "version": "0.3.0"},
+        {"id": "lib-core.crafting",               "version": "0.4.0"},
         {"id": "lib-core.crafting-display",       "version": "0.3.0"},
         {"id": "lib-asset.prototype-subterrain",  "version": "0.2.0"},
         {"id": "lib-asset.prototype-blob-geom",   "version": "0.1.0"},