Clojure stack traces via source registry + native frame walk

A direct-link build emits (jolt-register-source! short-name ns name file line)
once per fn def — at definition time, so zero per-call cost. On an uncaught
error the reporter walks Chez's native continuation frames (jolt-throw captures
the live continuation via call/cc; host conditions carry their own
&continuation), maps each frame's procedure name through the registry, and
prints a Clojure backtrace 'ns/name (file:line)'. Wired into both the cli and a
built binary's launcher.

Frames are keyed by the short munged fn name Chez actually reports (emit-fn's
letrec self-binding), not jv$ns$name; a cross-namespace collision degrades to
the bare frame name rather than a wrong attribution. The analyzer carries the
original form's position through defn macroexpansion onto the def node.

Calling a non-fn now throws a catchable ClassCastException (via jolt-throw)
naming the operator, instead of a raw Chez error.

Caveats (documented in source-registry.ss): names map only in direct-link/AOT
closed-world builds — the open-world -e/repl/run path falls back to the
top-level location; and pervasive TCO erases tail-call frames, so a mapped
trace shows only the non-tail spine. JOLT_DEBUG_FRAMES dumps raw frame names.

Re-mint (analyzer + backend); prelude byte-identical (direct-link off during
mint). Corpus rows certified, build-smoke asserts the trace.

host/chez/seq.ss

@@ -154,7 +154,12 @@
      => (lambda (m) (apply jolt-invoke m f args)))
     ((and (reified-methods f) (hashtable-ref (reified-methods f) "invoke" #f))
      => (lambda (m) (apply jolt-invoke m f args)))
-    (else (error 'invoke "not a fn" f))))
+    ;; calling a non-fn: a ClassCastException naming the operator, thrown via
+    ;; jolt-throw so it is catchable and carries the throw-site continuation for a
+    ;; stack trace.
+    (else (jolt-throw (jolt-host-throwable "java.lang.ClassCastException"
+                        (string-append (guard (e (#t "value")) (jolt-pr-str f))
+                                       " cannot be cast to clojure.lang.IFn"))))))
 
 ;; ============================================================================
 ;; map / filter / reduce / into / remove + range / take / concat / apply