core: spec 35-var batch A — 1.11 parsers, map/partition variants, with-redefs, ns fns

Fifteen vars from the spec coverage gap (docs/spec/coverage.md):
parse-long/parse-double/parse-boolean (strict validation; scan-number alone
accepts 0x10), newline, current-time-ms (host clock for time), update-keys/
update-vals (PHM base, collisions last-wins), partitionv/partitionv-all/
splitv-at (lazy seqs of vectors; splitv-at's tail stays a seq, matching the
reference), with-redefs/with-redefs-fn (roots restored on throw), time,
macroexpand (expand-1 to fixpoint), alias/ns-unalias (write BOTH alias stores
— require :as uses string-keyed :imports while ns-aliases reads :aliases;
split filed), ns-publics (symbol-keyed map; publics == interns, no privacy).

Three pre-existing bugs fixed along the way:
- (partition n step pad coll) misparsed pad as the coll and returned ()
- (require 'bare.symbol) rejected — only vector specs were accepted
- analyze-form leaked the interpreted analyzer's ns on a punt: a throw out of
  the analyzer left current-ns=jolt.analyzer and :compile-ns set, so the
  fallback interpretation resolved user vars against the wrong namespace
  (bit (var user-sym) under compile mode)

And one overlay-authoring landmine documented in-code: a 20-coll fn must not
use 30-macros macros (with-redefs-fn's dotimes compiled as a forward ref that
resolved to the macro fn at runtime) — loop/recur instead.

Gate: conformance 316x3 (+14 rows), suite 4324 pass / 78 clean (was 4081/72;
parse_*/update_* files now contribute), baselines raised, all specs+unit,
fixpoint, self-host, sci, staged. Coverage: missing-portable 35 -> 20.

jolt-core/clojure/core/30-macros.clj

@@ -57,6 +57,22 @@
 
 ;; defonce: define name only if it isn't already bound to a non-nil root;
 ;; returns the existing var untouched otherwise (matching the prior arm).
+;; time: evaluate expr, print the elapsed wall-clock, return the value.
+;; current-time-ms is the host's monotonic clock.
+(defmacro time [expr]
+  `(let [start# (current-time-ms)
+         ret# ~expr]
+     (println (str "Elapsed time: " (- (current-time-ms) start#) " msecs"))
+     ret#))
+
+;; with-redefs: temporary root rebinding, restored on exit (incl. throw).
+;; Builds (hash-map (var n1) v1 ...) — a call form, since map-literal forms
+;; can't carry call forms as keys.
+(defmacro with-redefs [bindings & body]
+  (let [pairs (reduce (fn [acc p] (conj (conj acc `(var ~(first p))) (second p)))
+                      [] (partition 2 bindings))]
+    `(with-redefs-fn (hash-map ~@pairs) (fn [] ~@body))))
+
 (defmacro defonce [name expr]
   `(let [v# (resolve (quote ~name))]
      (if (and v# (some? (var-get v#)))