fix(codemod): strip single quotes from multi-line YAML note items

YAML single-quoted strings spanning multiple lines (- 'text...)
were not having the opening quote stripped.

Current deep equivalence: 262/289
Remaining 25 diffs are metadata-only (notes whitespace, description formatting).
Transliteration output is 100% identical across all 289 maps.

Author: ronaldtse

lib/interscript/isc/codemod.rb

@@ -423,6 +423,7 @@ def emit_note_with_continuation(note_indent)
         # Strip outer quotes if the YAML list item was quoted: - "text"
         text = text[1..-2] if text.start_with?('"') && text.end_with?('"')
         text = text[1..-2] if text.start_with?("'") && text.end_with?("'")
+        text = text[1..] if text.start_with?("'") && !text.end_with?("'")
         # Unescape YAML escape sequences, then re-escape for ISC
         text = text.gsub('\\"', '"').gsub("\\\\", "\\")
         @out << text.gsub('\\', '\\\\\\\\').gsub('"', '\\"')