Fix whitespace in periodic summary by inlining albums list

Inline periodic_albums_list computation into periodic_summary_formatted
using {%- -%} whitespace control to prevent unwanted whitespace in the
formatted output. Add documentation about this Jinja2 pattern to CLAUDE.md.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

manifest.json

@@ -1,3 +1,3 @@
 {
-  "version": "1.23.2"
+  "version": "1.23.3"
 }