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/cljnim.nim

@@ -1,4 +1,4 @@
-# Clojure/Nim — AI-First Clojure Compiler
+# Bara Lang — AI-First Compiler
 import os, osproc, strutils, times
 import reader, emitter, types, repl, macros, deps, ai_assist, tui
 
@@ -213,7 +213,7 @@ proc main() =
   let args = commandLineParams()
   
   if args.len == 0:
-    echo "Clojure/Nim — AI-First Clojure Compiler"
+    echo "Bara Lang — AI-First Compiler"
     echo ""
     echo "Usage:"
     echo "  cljnim compile <file.clj> [output.nim]   Compile to Nim source"
@@ -222,7 +222,7 @@ proc main() =
     echo "  cljnim repl [--json]                     Start REPL (human or AI mode)"
     echo "  cljnim deps                              Resolve dependencies from deps.edn"
     echo "  cljnim -e '<code>'                       Evaluate expression"
-    echo "  cljnim ai '<description>'                Generate Clojure code with AI"
+    echo "  cljnim ai '<description>'                Generate Bara Lang code with AI"
     echo "  cljnim tui                               Start interactive TUI"
     echo ""
     echo "REPL Commands:"