Change hours_worked label to 'Hours worked per week' (#1609)

* Change hours_worked label to "Hours worked per week"

The variable represents weekly hours (used as hours/52 for weekly_hours
and hours*52 for annual calculations), so the label should reflect this.
Fixes #451.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Use 'Annual hours worked' label for hours_worked

hours_worked is annual: FRS input builds it as tothours * 52, and
weekly_hours divides it by WEEKS_IN_YEAR. A "per week" label would
misrepresent the variable by a factor of 52.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: vahid-ahmadi

changelog.d/451.md

@@ -0,0 +1 @@
+- Change `hours_worked` variable label to "Annual hours worked" for clarity.

policyengine_uk/variables/household/income/hours_worked.py

@@ -6,6 +6,6 @@
 class hours_worked(Variable):
     value_type = float
     entity = Person
-    label = "Total amount of hours worked by this person"
+    label = "Annual hours worked"
     definition_period = YEAR
     unit = "hour"