feat(budgets): add per-user personal budgets with strict isolation (#2891)

* feat(budgets): add per-user personal budgets with strict isolation

Families can now opt into personal budgets (toggleable via family
settings): each family member gets their own budget for a given
period instead of sharing a single family-wide budget.

- Add families.personal_budgets flag and budgets.user_id, with
  partial unique indexes so shared budgets (user_id IS NULL) and
  personal budgets (user_id IS NOT NULL) can't collide.
- Budget.find_or_bootstrap scopes lookup/creation by user when the
  family has personal_budgets enabled.
- Scope most_recent_initialized_budget (used to seed a new budget
  from the prior period) by user_id so one user's copy-forward never
  bleeds into another user's budget.
- budgets.user_id cascades on user deletion so personal budgets don't
  outlive their owner.

* feat(budgets): enforce user-specific budget ownership and cascade deletion

* feat(budgets): display user name for personal budgets in budget card on the plan section

* feat(budgets): enhance personal budgets display for admins with preview feature indication

* feat(budgets): enforce user-specific budget and category visibility for personal budgets

* feat(budgets): create budget section titles and add translations notice in preferences

* feat(budgets): let household and personal budgets coexist with sharing

Previously enabling personal_budgets made the shared household budget
unreachable. Budget.find_or_bootstrap now takes an explicit household:
flag so both can be resolved independently for the same period, with a
new household_budget_enabled family setting to opt out of the household
side and keep personal budgets only.

Adds a BudgetShare model (read_only/read_write) so a member can grant
another family member access to their personal budget, enforced via
Budget#viewable_by?/editable_by? across BudgetsController,
BudgetCategoriesController, PlansController, and the read-only API.
Preferences gains a Budget sharing card (gated on preview access like
the rest of the personal budgets UI) and an owner switcher pill (
Household / mine / shared-with-me) appears on the budget page and the
Plan hub card.

Also fixes personal budgets showing the same "actual spending" as the
household budget: actual spending/income now scope to the budget
owner's own accounts instead of the viewer's full accessible set,
via a new accounts: override on IncomeStatement.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* feat(budgets): enhance budget switcher with icons and improved styling

* feat(budgets): remove user name display from budget card and header

* feat(budgets): remove unique index on taggable_type and taggable_id in taggings

* feat(budgets): enhance budget sharing functionality and improve UI elements

* Collapse personal budget migrations

---------

Signed-off-by: JulienGourmet <69808509+jubbakka@users.noreply.github.com>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
Co-authored-by: sure-admin <sure-admin@splashblot.com>

app/controllers/budgets_controller.rb

@@ -1,5 +1,8 @@
 class BudgetsController < ApplicationController
+  include BudgetOwnership
+
   before_action :set_budget, only: %i[show edit update copy_previous]
+  before_action :ensure_budget_editable!, only: %i[edit update copy_previous]
 
   def index
     redirect_to_current_month_budget
@@ -7,6 +10,8 @@ class BudgetsController < ApplicationController
 
   def show
     @source_budget = @budget.most_recent_initialized_budget unless @budget.initialized?
+    @editable = @budget.editable_by?(Current.user)
+    @switch_options = budget_switch_options(@budget)
     @breadcrumbs = plan_breadcrumb_prefix + [ [ t("breadcrumbs.budgets"), nil ] ]
   end
 
@@ -16,12 +21,12 @@ class BudgetsController < ApplicationController
 
   def update
     @budget.update!(budget_params)
-    redirect_to budget_budget_categories_path(@budget)
+    redirect_to budget_budget_categories_path(@budget, **budget_owner_query)
   end
 
   def copy_previous
     if @budget.initialized?
-      redirect_to budget_path(@budget), alert: t("budgets.copy_previous.already_initialized")
+      redirect_to budget_path(@budget, **budget_owner_query), alert: t("budgets.copy_previous.already_initialized")
       return
     end
 
@@ -29,9 +34,9 @@ class BudgetsController < ApplicationController
 
     if source_budget
       @budget.copy_from!(source_budget)
-      redirect_to budget_budget_categories_path(@budget), notice: t("budgets.copy_previous.success", source_name: source_budget.name)
+      redirect_to budget_budget_categories_path(@budget, **budget_owner_query), notice: t("budgets.copy_previous.success", source_name: source_budget.name)
     else
-      redirect_to budget_path(@budget), alert: t("budgets.copy_previous.no_source")
+      redirect_to budget_path(@budget, **budget_owner_query), alert: t("budgets.copy_previous.no_source")
     end
   end
 
@@ -54,12 +59,12 @@ class BudgetsController < ApplicationController
 
     def set_budget
       start_date = Budget.param_to_date(params[:month_year], family: Current.family)
-      @budget = Budget.find_or_bootstrap(Current.family, start_date: start_date, user: Current.user)
+      @budget = resolve_budget(start_date)
       raise ActiveRecord::RecordNotFound unless @budget
     end
 
     def redirect_to_current_month_budget
-      current_budget = Budget.find_or_bootstrap(Current.family, start_date: Date.current, user: Current.user)
-      redirect_to budget_path(current_budget)
+      current_budget = resolve_budget(Date.current)
+      redirect_to budget_path(current_budget, **budget_owner_query)
     end
 end