chore: do not track another project's ledger or runtime locks

A crew ledger for a different project appeared under docs/state/ from a
cross-repository write, and lock files live there for the duration of one
operation. Neither is content this repository owns, and both made the
working tree read dirty to the release pre-flight check.

The stray ledger is left on disk rather than removed; it is another
session's artifact to triage.

Author: Simon-McIntosh

.gitignore

@@ -33,3 +33,10 @@ htmltest/
 
 # expert-review reply PDF (rendered artifact, not version-controlled)
 docs/expert-review-reply.pdf
+
+# Reckon writes each project's crew ledger under its own repository. A
+# subdirectory named for a different project is a cross-repository write, not
+# content this repository owns.
+docs/state/imas-codex/
+# Lock files are runtime state for the duration of one operation.
+docs/.reckon/locks/