Standardize Category Labels (e.g., "Food" vs "food")

Description:
Currently, categories are case-sensitive and inconsistent, resulting in duplicates like "Food" and "food".

Proposed Solution:

Normalize category inputs by capitalizing or lowercasing them.

On form submission, check and merge similar entries.

Benefits:

Cleaner data.

Prevents duplicate categories.

Enhances chart grouping and reporting.

Start by locating the category input and form-submission handling, then inspect how categories are used for chart grouping and reporting. Clarify whether capitalization or lowercasing is the project convention and how existing duplicates should merge. Done means equivalent labels no longer create separate categories and grouping remains consistent.

Written by the indexing model from the issue text.