Mostly vibe coded (Opus 4.6) set of paredit-like sexp manipulation tools.

• Added paredit-style structural editing tools (wrap, unwrap, raise, slurp, barf, kill, transpose, split, join).
• Added sexp-replace, sexp-insert-before, sexp-insert-after for code replacement and insertion.
• Added sexp-show-structure and sexp-get-enclosing for code inspection.
• Added sexp-to-json-ast for CST-based JSON AST output.
• Added Eclector-based CST parser with source position tracking.
• Added devcontainer configuration