refactor: remove the dead state-to-todo mapping subsystem

`pearl-state-to-todo-mapping` and its derived regex stopped doing real work once keyword rendering moved to slugifying the Linear state name (`pearl--state-name-to-keyword`) and the keyword-to-state direction moved to resolving through the team's workflow states. The defcustom fed only `pearl--get-todo-states-pattern`, which had no caller left, and the two cache vars existed only to serve that dead function. State extraction reads `org-get-todo-state` off the buffer's `#+TODO` line, so nothing live touched the mapping.

I removed the defcustom, both cache vars, and the dead function, and dropped the three pattern tests that exercised it. Removing the defcustom orphaned the mapping bindings that ~12 test setup macros still carried. They were passing through slugification rather than the map, so I stripped them too and kept the `org-todo-keywords` bindings the temp buffers actually need. Also dropped the stale README config row.

1 files changed, 2 insertions, 4 deletions

diff --git a/tests/test-pearl-fields.el b/tests/test-pearl-fields.el
index 2ad9679..53e4ac8 100644
--- a/tests/test-pearl-fields.el
+++ b/tests/test-pearl-fields.el
@@ -31,11 +31,9 @@
 (require 'cl-lib)
 
 (defmacro test-pearl--in-org (content &rest body)
-  "Run BODY in an org-mode temp buffer holding CONTENT, default mapping bound."
+  "Run BODY in an org-mode temp buffer holding CONTENT."
   (declare (indent 1))
-  `(let ((pearl-state-to-todo-mapping
-          '(("Todo" . "TODO") ("In Progress" . "IN-PROGRESS") ("Done" . "DONE")))
-         (org-todo-keywords '((sequence "TODO" "IN-PROGRESS" "|" "DONE"))))
+  `(let ((org-todo-keywords '((sequence "TODO" "IN-PROGRESS" "|" "DONE"))))
      (with-temp-buffer
        (insert ,content)
        (org-mode)