Phase 3a: spawn/record initializers use ':' (Rule A)

Comp = { f = v }  ->  Comp { f: v }. record() requires ':' and parse_spawn()
drops the '=' before the record; '=' is now assignment/binding only. Records
appear only in games, so the compiler seed is unaffected.

Migration: tools/ludic-tools/migrate_records.c (spawn-context aware). Verified
every golden byte-identical, old '=' form rejected, reseeded, test.sh 14/14.
Docs updated (LANGUAGE.md, BOOTSTRAP.md R2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/hello.ludic

@@ -6,12 +6,12 @@ game Hello {
 
   system Boot phase Start {
     spawn Mob {
-      Pos = { x = 3, y = 4 }
-      Vel = { dx = 1, dy = 0 }
+      Pos { x: 3, y: 4 }
+      Vel { dx: 1, dy: 0 }
     }
     spawn Mob {
-      Pos = { x = 10, y = 2 }
-      Vel = { dx = 0, dy = 1 }
+      Pos { x: 10, y: 2 }
+      Vel { dx: 0, dy: 1 }
     }
   }