Fix RTD docs build failure caused by Sphinx 9.x compatibility

Set default_role = 'any' in docs/conf.py. Sphinx 9.0 removed implicit
handling of bare backtick text when no default role is configured,
causing the build to fail with "cannot determine default role!".

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: CodeReclaimers

docs/conf.py

@@ -105,7 +105,7 @@
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.
-#default_role = None
+default_role = 'any'
 
 # If true, '()' will be appended to :func: etc. cross-reference text.
 #add_function_parentheses = True