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, 0 insertions, 1 deletions

diff --git a/README.org b/README.org
index 88eaa99..ad6c5a6 100644
--- a/README.org
+++ b/README.org
@@ -279,7 +279,6 @@ Most users only need an API key and an output path. The rest are knobs for teams
 | =pearl-org-file-path=         | Active Org output file                            |
 | =pearl-default-team-id=       | Default team for issue creation                   |
 | =pearl-saved-queries=         | Named local issue queries                         |
-| =pearl-state-to-todo-mapping= | Linear state to Org keyword mapping               |
 | =pearl-max-issue-pages=       | Pagination cap, 100 issues per page               |
 | =pearl-request-timeout=       | Synchronous request timeout in seconds            |
 | =pearl-fold-after-update=     | Re-fold the active page after fetch/refresh       |