fix: threading macros, REPL stability, and CI coverage

- fix(emitter): emitFnWrapper now uses runtimeName for builtin operators
- fix(emitter): map/reduce handlers support variadic runtime functions (+, -, etc.)
- fix(emitter): variadic runtime functions list extracted to variadicRuntimeFns constant
- fix(macros): restore correct thread-first behavior (->) and fix result shadowing
- fix(macros): and/or/as->/some->/some->> macro result variable fixes
- fix(repl): add macroexpand step before interpreter eval
- fix(runtime): cljReduceSeq handles nil init (uses first coll element)
- fix(eval): add macroexpand/macroexpand-1 special forms to interpreter
- fix(eval): add macros module import for macroexpand access
- fix(warnings): eliminate ResultShadowed and UnusedImport warnings
- chore(.gitignore): remove artifact entries (-o, =0.4.0), unignore lib/bring_http.nim
- chore(ci): run all examples + threading macro + macroexpand REPL smoke tests

lib/cljnim_runtime.nim

@@ -1476,9 +1476,17 @@ proc cljFilterSeq*(f: proc(args: seq[CljVal]): CljVal, coll: seq[CljVal]): seq[C
       result.add(item)
 
 proc cljReduceSeq*(f: proc(args: seq[CljVal]): CljVal, init: CljVal, coll: seq[CljVal]): CljVal =
-  result = init
-  for item in coll:
-    result = f(@[result, item])
+  if coll.len == 0:
+    return init
+  var i = 0
+  if init.isNil or init.kind == ckNil:
+    result = coll[0]
+    i = 1
+  else:
+    result = init
+  while i < coll.len:
+    result = f(@[result, coll[i]])
+    i += 1
 
 proc cljMap*(f: proc(args: seq[CljVal]): CljVal, coll: CljVal): CljVal =
   if coll.isNil: return cljList(@[])