Make the REPL read multi-line forms and render real error messages

The REPL evaluated one line at a time, so a form split across lines
(e.g. `(+` then `1 2)`) raised instead of waiting. The read loop now
accumulates lines until delimiters are balanced — skipping string,
char, regex and comment context — printing a `... ` continuation prompt
for each extra line.

Reader/runtime errors rendered as Chez's "attempt to apply
non-procedure #[chez-pmap...]" instead of their real message. Two causes:

jolt-throw raised the thrown value raw. When a throw crossed the host
`eval` boundary, Chez re-wrapped the non-condition into a compound
condition whose message extraction applies the value, losing the message
and crashing on ex-info's empty-map :data. jolt-throw now raises a
&jolt-throw condition wrapping the value; catch (lowered to `guard`),
jolt-report-uncaught and jolt-render-throwable unwrap it back via
jolt-unwrap-throw, so ex-data/ex-message and the backtrace tag survive.

Every reader/post-prelude EOF-throw site used `(empty-pmap)` (with
parens), applying the empty-map value as a procedure and crashing during
ex-info construction before jolt-throw ran. Fixed to `empty-pmap`.

Re-minted the seed; smoke 23/23, unit 574/574.

jolt-core/jolt/analyzer.clj

@@ -258,6 +258,7 @@
     (let [n {:op :try :body (analyze-seq ctx @body env)}
           n (if (seq @catches)
               (let [evar-name (gen-name "catch")
+                    raw-name (gen-name "catch-raw")
                     evar (symbol evar-name)
                     dispatch
                     (reduce
@@ -278,6 +279,7 @@
                       (list 'throw evar)
                       (reverse @catches))]
                 (assoc n :catch-sym evar-name
+                         :catch-raw-sym raw-name
                          :catch-body (analyze-seq ctx (list dispatch)
                                                   (add-locals env [evar-name]))))
               n)