build: dynamically tangle to INSTALL_DIR without copying .org files

- Updated all 150+ :tangle headers across harness/ and skills/ to use elisp (expand-file-name) to target INSTALL_DIR dynamically.
- Cleaned up environment/ directory depth by moving memory-image.lisp to state/.
- Moved test scripts to tests/ and deleted redundant chat scripts.

skills/org-skill-homoiconic-memory.org

@@ -11,7 +11,7 @@ The *Homoiconic Memory* skill provides the core persistence layer for OpenCortex
 
 * Implementation
 
-#+begin_src lisp :tangle ./org-skill-homoiconic-memory.lisp
+#+begin_src lisp :tangle (expand-file-name "org-skill-homoiconic-memory.lisp" (concat (or (getenv "INSTALL_DIR") ".") "/skills"))
 
 (defun memory-org-to-json (source)
   "Converts Org-mode source to JSON AST."