Replace the uprated rent target with a direct current-year ACS aggregate

[MaxGhenis]

The current rent target is a hardcoded ACS-derived total uprated by CPI. If we keep rent as a calibration anchor, we should at least use a direct current-year official aggregate rather than uprating a stale benchmark.

Why the current target is weak:

• It is not administrative.
• The current value is an uprated aggregate rather than a direct current-year measurement.
• ACS remains the official broad rent source, but if we use it, we should use the current-year ACS aggregate gross rent directly.

Proposed change:

• Replace the current hardcoded uprated total with a direct current-year ACS aggregate gross rent benchmark.
• If we want to move toward an admin-first target set, demote rent from hard calibration entirely, because there is no clean administrative total for national rent paid.

Primary sources:

• ACS subject definitions (gross rent): https://www2.census.gov/programs-surveys/acs/tech_docs/subject_definitions/2024_ACSSubjectDefinitions.pdf
• ACS program overview: https://www.census.gov/programs-surveys/acs