test: restructure into unit / integration / spec layers + shared harness

Reorganize the flat 49-file test/ into three layers (jpm test recurses, so all
are still discovered):
- test/unit/        white-box component tests (reader, evaluator, types,
                    persistent-map, lazy-seq, macro, interop, compiler)
- test/integration/ cross-cutting + regression batteries (conformance, jank,
                    sci-bootstrap/runtime, features, systematic-coverage, api,
                    core, namespaces, ported clojure suites) and
   .../ports/       ported clojure/cljs test batches pending consolidation
- test/spec/        the behavioral contract (built out in following commits)
- test/support/harness.janet  shared defspec table runner (cases compared via
                    Jolt's own =, with a :throws sentinel) + expect= helpers

Files moved with git mv (history preserved) and import paths fixed for depth.
jpm test green. README Test section updated.

Next: build out test/spec/ to cover the public API area-by-area, mining the
integration batteries and filling gaps.

test/integration/core-test.janet

@@ -0,0 +1,122 @@
+(use ../../src/jolt/types)
+(use ../../src/jolt/pv)
+(use ../../src/jolt/plist)
+(use ../../src/jolt/reader)
+(use ../../src/jolt/evaluator)
+(use ../../src/jolt/core)
+
+# Normalize jolt collection results to Janet tuples so Janet-level deep=/= can
+# compare against tuple literals regardless of the (pvec/plist) representation.
+(defn norm [x]
+  (cond
+    (pvec? x) (tuple ;(map norm (pv->array x)))
+    (plist? x) (tuple ;(map norm (pl->array x)))
+    (tuple? x) (tuple ;(map norm x))
+    (array? x) (tuple ;(map norm x))
+    x))
+
+# Helper: create a fresh bootstrapped context
+(defn make-boot-ctx []
+  (let [ctx (make-ctx)]
+    (init-core! ctx)
+    ctx))
+
+# Helper: parse + eval
+(defn eval-str [ctx s]
+  (let [form (parse-string s)]
+    (norm (eval-form ctx @{} form))))
+
+(print "1: predicates...")
+(let [ctx (make-boot-ctx)]
+  (assert (= true (eval-str ctx "(nil? nil)")) "nil?")
+  (assert (= false (eval-str ctx "(nil? 1)")) "nil? false")
+  (assert (= true (eval-str ctx "(string? \"hello\")")) "string?")
+  (assert (= true (eval-str ctx "(number? 42)")) "number?")
+  (assert (= true (eval-str ctx "(fn? inc)")) "fn?")
+  (assert (= true (eval-str ctx "(keyword? :foo)")) "keyword?")
+  (assert (= false (eval-str ctx "(keyword? 1)")) "keyword? false")
+  (assert (= true (eval-str ctx "(zero? 0)")) "zero?")
+  (assert (= true (eval-str ctx "(pos? 1)")) "pos?")
+  (assert (= true (eval-str ctx "(neg? -1)")) "neg?")
+  (assert (= true (eval-str ctx "(even? 2)")) "even?")
+  (assert (= true (eval-str ctx "(odd? 1)")) "odd?")
+  (assert (= true (eval-str ctx "(empty? [])")) "empty? vector")
+  (assert (= false (eval-str ctx "(empty? [1])")) "empty? non-empty"))
+(print "  passed")
+
+(print "2: math...")
+(let [ctx (make-boot-ctx)]
+  (assert (= 0 (eval-str ctx "(+)")) "+ 0 args")
+  (assert (= 5 (eval-str ctx "(+ 2 3)")) "+ 2 args")
+  (assert (= 10 (eval-str ctx "(+ 1 2 3 4)")) "+ varargs")
+  (assert (= -5 (eval-str ctx "(- 5)")) "- unary")
+  (assert (= 2 (eval-str ctx "(- 5 3)")) "- binary")
+  (assert (= 6 (eval-str ctx "(* 2 3)")) "*")
+  (assert (= 1 (eval-str ctx "(*)")) "* 0 args")
+  (assert (= 42 (eval-str ctx "(inc 41)")) "inc")
+  (assert (= 40 (eval-str ctx "(dec 41)")) "dec")
+  (assert (= 4 (eval-str ctx "(max 1 4 2)")) "max"))
+(print "  passed")
+
+(print "3: comparison...")
+(let [ctx (make-boot-ctx)]
+  (assert (= true (eval-str ctx "(= 1 1)")) "= same")
+  (assert (= false (eval-str ctx "(= 1 2)")) "= diff")
+  (assert (= true (eval-str ctx "(= 1 1 1)")) "= multi same")
+  (assert (= false (eval-str ctx "(= 1 2 1)")) "= multi diff")
+  (assert (= true (eval-str ctx "(not= 1 2)")) "not="))
+(print "  passed")
+
+(print "4: collections...")
+(let [ctx (make-boot-ctx)]
+  (assert (= 3 (eval-str ctx "(count [1 2 3])")) "count vector")
+  (assert (= 1 (eval-str ctx "(first [1 2 3])")) "first")
+  (assert (deep= [2 3] (eval-str ctx "(rest [1 2 3])")) "rest")
+  (assert (= nil (eval-str ctx "(next [1])")) "next singleton")
+  (assert (deep= [1 2 3] (eval-str ctx "(conj [1 2] 3)")) "conj vector")
+  (assert (= 1 (eval-str ctx "(get {:a 1} :a)")) "get map")
+  (assert (= 2 (eval-str ctx "(get [1 2 3] 1)")) "get vector")
+  (assert (= :default (eval-str ctx "(get {:a 1} :b :default)")) "get default")
+  (assert (deep= {:a 1 :c 3} (eval-str ctx "(assoc {:a 1} :c 3)")) "assoc")
+  (assert (deep= {:a 1} (eval-str ctx "(dissoc {:a 1 :b 2} :b)")) "dissoc"))
+(print "  passed")
+
+(print "5: seq ops...")
+(let [ctx (make-boot-ctx)]
+  (assert (deep= [2 3 4] (eval-str ctx "(map inc [1 2 3])")) "map")
+  (assert (deep= [2 4] (eval-str ctx "(filter even? [1 2 3 4])")) "filter")
+  (assert (= 6 (eval-str ctx "(reduce + [1 2 3])")) "reduce")
+  (assert (= 10 (eval-str ctx "(reduce + 4 [1 2 3])")) "reduce with val")
+  (assert (deep= [1 2] (eval-str ctx "(take 2 [1 2 3 4])")) "take")
+  (assert (deep= [3 4] (eval-str ctx "(drop 2 [1 2 3 4])")) "drop")
+  (assert (deep= [1 2] (eval-str ctx "(take-while (fn* [x] (<= x 2)) [1 2 3 4])")) "take-while"))
+(print "  passed")
+
+(print "6: range...")
+(let [ctx (make-boot-ctx)]
+  (assert (deep= [0 1 2 3 4] (eval-str ctx "(range 5)")) "range end")
+  (assert (deep= [2 3 4] (eval-str ctx "(range 2 5)")) "range start end"))
+(print "  passed")
+
+(print "7: higher-order...")
+(let [ctx (make-boot-ctx)]
+  (assert (= 42 (eval-str ctx "(identity 42)")) "identity")
+  (assert (= 42 (eval-str ctx "(let* [f (constantly 42)] (f))")) "constantly")
+  (assert (= 3 (eval-str ctx "(let* [f (comp inc inc)] (f 1))")) "comp")
+  (assert (deep= [2 0] (eval-str ctx "(let* [f (juxt inc dec)] (f 1))")) "juxt"))
+(print "  passed")
+
+(print "8: str...")
+(let [ctx (make-boot-ctx)]
+  (assert (= "hello" (eval-str ctx "(str \"hello\")")) "str")
+  (assert (= "hello42" (eval-str ctx "(str \"hello\" 42)")) "str concat"))
+(print "  passed")
+
+(print "9: atom...")
+(let [ctx (make-boot-ctx)]
+  (assert (= 1 (eval-str ctx "(let* [a (atom 1)] (deref a))")) "atom + deref")
+  (assert (= 42 (eval-str ctx "(let* [a (atom 1)] (reset! a 42) (deref a))")) "reset!")
+  (assert (= 2 (eval-str ctx "(let* [a (atom 1)] (swap! a inc) (deref a))")) "swap!"))
+(print "  passed")
+
+(print "\nAll core tests passed!")