feat: add fullscreen TUI and project updates

- New TUI screens: Main Menu, Compile, Run, REPL, AI Generator, AI Settings, Help
- AI configuration persisted in ~/.config/cljnim/config.json
- Added illwill dependency for terminal UI
- Updated experiments, examples, docs, and core modules

lib/cljnim_pvec.nim

@@ -99,17 +99,6 @@ proc pushLeaf[T](node: PVecNode[T], index: int, shift: int, val: seq[T]): PVecNo
     
     result.children[childIdx] = child
 
-proc newPath[T](shift: int, leaf: PVecNode[T]): PVecNode[T] =
-  # Create a path of empty internal nodes from shift down to leaf level
-  if shift == 0:
-    return leaf
-  var node = newInternalNode[T](@[leaf])
-  var level = BRANCHING_BITS
-  while level < shift:
-    node = newInternalNode[T](@[node])
-    level += BRANCHING_BITS
-  return node
-
 proc pvecConj*[T](v: PersistentVector[T], val: T): PersistentVector[T] =
   result = v
   result.count += 1