feat: module 05 assemble

Cards become JSON data in course/cards (one file per card, validated
against card.schema.json and the catalog); the M5 references load them
via registerCards and interpret effects, replacing content closures.
Adds assemble(base, donor, half), the assemble/buffHand effects with an
injected chooser, Fleshshape as the data-only Expansion Drop, and stages
course/cards in verify-references and start-module.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

course/schema/card.schema.json

@@ -1,5 +1,5 @@
 {
-  "$comment": "Structured card text. A trigger clause applies to the effect clauses after it until the next trigger/keyword/aura. split divides top (text[0:split]) from bottom (text[split:]).",
+  "$comment": "Structured card text. A trigger clause applies to the effect clauses after it until the next trigger/keyword/aura. split divides top (text[0:split]) from bottom (text[split:]). Effect assemble: put a minion into your hand, chosen from the pool of minions matching filter (filter.trigger: it has a trigger clause with that on), with half its text replaced (Module 5). Effect buffHand: give every minion in your hand +attack/+health.",
   "type": "object",
   "required": ["name", "type", "cost", "text", "split"],
   "properties": {
@@ -36,7 +36,10 @@
                 { "type": "object", "required": ["type", "amount"], "properties": { "type": { "const": "gainArmor" }, "amount": { "type": "integer", "minimum": 1 } } },
                 { "type": "object", "required": ["type", "target", "amount"], "properties": { "type": { "const": "gainAttack" }, "target": { "enum": ["self", "allMinions", "allOtherMinions", "allOtherCharacters", "enemyHero", "chosen"] }, "amount": { "type": "integer" } } },
                 { "type": "object", "required": ["type", "target"], "properties": { "type": { "const": "destroy" }, "target": { "enum": ["self", "allMinions", "allOtherMinions", "allOtherCharacters", "enemyHero", "chosen"] } } },
-                { "type": "object", "required": ["type", "word", "at"], "properties": { "type": { "const": "spawnText" }, "word": { "type": "string" }, "at": { "const": "self" } } }
+                { "type": "object", "required": ["type", "word", "at"], "properties": { "type": { "const": "spawnText" }, "word": { "type": "string" }, "at": { "const": "self" } } },
+                { "type": "object", "required": ["type", "filter"], "properties": { "type": { "const": "assemble" }, "filter": { "type": "object", "properties": {
+                    "trigger": { "enum": ["deathrattle", "battlecry", "selfDamaged", "friendlyMinionDamaged", "anyMinionDamaged", "heroDamaged", "endOfTurn"] } } } } },
+                { "type": "object", "required": ["type", "attack", "health"], "properties": { "type": { "const": "buffHand" }, "attack": { "type": "integer", "minimum": 0 }, "health": { "type": "integer", "minimum": 0 } } }
               ] } } }
         ]
       }