Phase 1-4: Reader, Runtime, Macros, Nim Interop — 543x faster than JVM Clojure

- Reader: maps, sets, syntax-quote, dispatch macros, metadata
- Runtime: CljVal type system, 80+ core functions (collections, strings, math, IO)
- Emitter: full CljVal-based code generation, macro expansion, inline fns
- Macros: defmacro with compile-time evaluator, ->, ->>, and, or, when, cond, for, doseq
- Nim Interop: nim/module/function syntax, auto-import, type mapping
- CLI: cljnim -e '<code>' for quick evaluation
- Tests: 60 unit tests (reader + emitter)
- Benchmarks: AOT suite showing 543x startup, 679x factorial vs JVM Clojure
- CI: GitLab CI pipeline
- Runtime library: lib/cljnim_runtime.nim (1070+ lines)

benchmarks/factorial.clj

@@ -0,0 +1,6 @@
+(defn factorial [n]
+  (if (<= n 1)
+    1
+    (* n (factorial (- n 1)))))
+
+(println (factorial 20))