fix: clj_ prefix for identifiers + try/catch/finally fixes

- #9: Add clj_ prefix to all mangled identifiers to avoid Nim
  case-insensitive name conflicts (parseQueryString ≡ parse_query_string)
- #11: Fix finally block - discard expression results
- #11: Fix catch handler - use original name for scope tracking
- Fix loop handler - use original name for addToScope
- Update emitter tests for clj_ prefix

tests/test_emitter.nim

@@ -43,13 +43,13 @@ suite "Emitter - Basic Values":
     registerGlobal("x")
     let v = cljSymbol("x")
     let code = emitExpr(v)
-    check code == "x"
+    check code == "clj_x"
 
   test "emit mangled symbol":
     registerGlobal("my-var")
     let v = cljSymbol("my-var")
     let code = emitExpr(v)
-    check code == "my_var"
+    check code == "clj_my_var"
 
   test "emit vector":
     let v = cljVector(@[cljInt(1), cljInt(2)])
@@ -70,12 +70,12 @@ suite "Emitter - Special Forms":
   test "emit def":
     let v = read("(def x 42)")
     let code = emitExpr(v)
-    check "let x" in code
+    check "let clj_x" in code
 
   test "emit defn":
     let v = read("(defn square [x] (* x x))")
     let code = emitExpr(v)
-    check "proc square" in code
+    check "proc clj_square" in code
 
   test "emit if":
     let v = read("(if true 1 2)")
@@ -161,14 +161,14 @@ suite "Emitter - Program":
   test "emitProgram with defs and main":
     let forms = readAll("(def x 42) (println x)")
     let code = emitProgram(forms)
-    check "let x" in code
+    check "let clj_x" in code
     check "when isMainModule" in code
 
   test "emitProgram multiple defs":
     let forms = readAll("(def a 1) (def b 2)")
     let code = emitProgram(forms)
-    check "let a" in code
-    check "let b" in code
+    check "let clj_a" in code
+    check "let clj_b" in code
 
 suite "Emitter - Map Literals":
   test "emit empty map":