Both Uncategorized and Other Investments are synthetic categories with
id=nil. When expense_totals_by_category indexes by category.id, Other
Investments overwrites Uncategorized at the nil key, causing uncategorized
actual spending to always return 0.
Use category.name as fallback key (id || name) to differentiate the two
synthetic categories in all hash builders and lookup sites.
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>