Make categories global (#1160)

* Make categories global

This solves us A LOT of cash flow and budgeting problems.

* Update schema.rb

* Update auto_categorizer.rb

* Update income_statement.rb

* FIX budget sub-categories

* FIX sub-categories and tests

* Add 2 step migration

db/migrate/20260308113006_remove_classification_from_categories.rb

@@ -0,0 +1,9 @@
+class RemoveClassificationFromCategories < ActiveRecord::Migration[7.2]
+  def up
+    rename_column :categories, :classification, :classification_unused
+  end
+
+  def down
+    rename_column :categories, :classification_unused, :classification
+  end
+end