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

src/emitter.nim

@@ -1,4 +1,4 @@
-# Clojure → Nim Emitter
+# Bara Lang → Nim Emitter
 import strutils, sets, algorithm
 import types
 import macros
@@ -2059,7 +2059,7 @@ proc emitProgramInternal(forms: seq[CljVal]): string =
   pushScope()
   requiredImports = initHashSet[string]()
   var headerLines: seq[string] = @[
-    "# Generated by Clojure/Nim",
+    "# Generated by Bara Lang",
     "import cljnim_runtime",
   ]