chore: rebrand Clojure/Nim → Bara Lang across codebase

- Bulk replace Clojure/Nim → Bara Lang in src/, lib/, examples/, benchmarks/,
  experiments/, books/, LICENSE, cljnim.nimble, PLAN.md, AI_AGENT.md
- Rename book chapters: 05-clojure-nim.md → 05-bara-lang.md (en + bg)
- Update all chapter index links and anchors
- Replace project-specific 'Clojure' references with 'Bara Lang' in
  experiments/, src/ai_assist.nim, src/tui_screens.nim, src/emitter.nim,
  src/reader.nim, src/types.nim, lib/cljnim_runtime*.nim
- Keep legitimate JVM Clojure/ClojureScript/Clojure CLR references intact

experiments/native-lib/native_wrappers.nim

@@ -1,9 +1,9 @@
-# C-friendly wrappers around Clojure-generated code
+# C-friendly wrappers around Bara Lang-generated code
 # Exports plain C types (int, char*) instead of CljVal
 
 import cljnim_runtime
 
-# Import the generated Clojure functions
+# Import the generated Bara Lang functions
 include build/math
 
 proc c_square*(x: cint): cint {.exportc, dynlib.} =