Phase 4: deftype/defrecord completion

- evaluator.janet: fix set! to handle (.-field obj) shorthand
  Previously only recognized (. obj -field) format
- core.janet: rewrite core-defrecord to emit (deftype ...) instead of
  plain def with array-map constructor
- core.janet: fix core-map? to recognize deftype table instances
  (and returns last truthy, not boolean true — wrap in if)
- core.janet: fix core-count to skip :jolt/deftype key for records
- core.janet: add ->TypeName arrow factory that calls TypeName.
  constructor via Clojure form emission
- 11 new tests: deftype fields/mutation/instance?, defrecord
  construction/map-behavior/fields/factories, record equality
- map->TypeName factory deferred (needs get/symbol resolution fix)
- 317 tests pass, 0 failures

.dirge/memory/MEMORY.md

@@ -7,3 +7,5 @@ Phase 2 (PersistentHashMap): Live in src/jolt/phm.janet — separate module impo
 Macro expansion: resolve-macro at analyze time → expand → re-analyze. Loop: (do (var _loop_N nil) (set _loop_N (fn [params] body)) (_loop_N vals...)). Recur: emits (loop-name args...) via :loop-name in AST.
 §
 Test files: test/phase6-final.janet (47 tests, 58 assertions — collections, math, predicates, comparison, seq ops, special forms, macros, complex nesting). Phase 1 tests appended to test/compiler-test.janet (ns accessors, ns form extensions). All 317 tests pass.
+§
+Phase 3 (Var system): find-var (ctx-based, resolve-q/nq symbol), alter-meta!, reset-meta!, var-get/var-set/var?/alter-var-root all in types.janet + evaluator dispatch arms + core-bindings wrappers. core-meta fixed: (var? x) branch → var-meta, struct? branch → :meta. 10 tests pass.