fix(emitter): avoid clj_ prefix on nim/ interop identifiers

The clj_ prefix added in fb8928e broke nim/module/proc interop because
native Nim identifiers were being mangled to clj_foo instead of foo.

- Extract sanitizeNimIdent from mangleName (does all cleanups except prefix)
- Use sanitizeNimIdent for nim/ interop function chains
- Regular Clojure symbols still get clj_ prefix via mangleName

Fixes BRing bringRunServer and other native Nim proc calls.

src/emitter.nim

@@ -35,7 +35,8 @@ proc resolveNsAlias*(name: string): string =
 type
   EmitterError* = object of CatchableError
 
-proc mangleName*(name: string): string =
+proc sanitizeNimIdent*(name: string): string =
+  ## Sanitize a string to be a valid Nim identifier, without the clj_ prefix.
   result = ""
   for c in name:
     case c
@@ -79,8 +80,9 @@ proc mangleName*(name: string): string =
                      "interface", "lambda", "open", "quit", "result", "nil", "end"]
   if result in nimKeywords:
     result = result & "1"
-  # Prefix to avoid conflicts with Nim identifiers (case-insensitive + underscore ignoring)
-  result = "clj_" & result
+
+proc mangleName*(name: string): string =
+  result = "clj_" & sanitizeNimIdent(name)
 
 proc pushScope() =
   scopeStack.add(initHashSet[string]())
@@ -1958,10 +1960,11 @@ proc emitSpecialForm(items: seq[CljVal], indent: int): string =
       let parts = op.replace(".", "/").split("/")
       if parts.len >= 3:
         let module = parts[1]
-        # Mangle each part of the function chain for Nim identifier validity
+        # Sanitize each part of the function chain for Nim identifier validity
+        # (native Nim identifiers must NOT get the clj_ prefix)
         var mangledParts: seq[string] = @[]
         for p in parts[2..^1]:
-          mangledParts.add(mangleName(p))
+          mangledParts.add(sanitizeNimIdent(p))
         var funcChain = mangledParts.join(".")
         # Strip ? suffix (Clojure convention) — not valid in Nim
         if funcChain.endsWith("?"):