build: embed test scripts into org files and purge tests directory

- Embedded run-all-tests.lisp into harness/package.org.
- Deleted the tests/ directory and orphaned Python test scripts, as all other test files are correctly tangled from their parent org files.

tests/immune-system-tests.lisp

@@ -1,23 +0,0 @@
-(defpackage :opencortex-immune-system-tests
-  (:use :cl :fiveam :opencortex)
-  (:export #:immune-suite))
-
-(in-package :opencortex-immune-system-tests)
-
-(def-suite immune-suite
-  :description "Verification of the Immune System (Core Error Hooks)")
-
-(in-suite immune-suite)
-
-(test loop-error-injection
-  "Verify that a crash in think/decide triggers a :loop-error stimulus."
-  (clrhash opencortex::*skills-registry*)
-  (opencortex:defskill :evil-skill
-    :priority 100
-    :trigger (lambda (ctx) (eq (getf (getf ctx :payload) :sensor) :user-input))
-    :probabilistic (lambda (ctx) (error "CRITICAL BRAIN FAILURE"))
-    :deterministic nil)
-  (opencortex:harness-log "CLEAN LOG")
-  (opencortex:process-signal '(:type :EVENT :payload (:sensor :user-input)))
-  (let ((logs (opencortex:context-get-system-logs 20)))
-    (is (not (null (find-if (lambda (line) (search "CRITICAL BRAIN FAILURE" line)) logs))))))