Add Pennsylvania property tax/rent rebate

[daphnehanse11]

Summary

• Adds Pennsylvania's standard Property Tax/Rent Rebate eligibility and income-based rebate table for 2025 claims.
• Models senior, surviving-spouse, and disabled eligibility, and caps the standard rebate by rent/property taxes paid.
• Adds focused eligibility and rebate amount tests.

Closes #8181.

Note: this PR models the standard rebate table and leaves supplemental rebates for follow-up.

Tests

• /Users/daphnehansell/Documents/GitHub/policyengine-us/.venv/bin/python policyengine_us/tests/test_batched.py policyengine_us/tests/policy/baseline/gov/states/pa/tax/property/property_tax_or_rent_rebate --batches 1
• /Users/daphnehansell/Documents/GitHub/policyengine-us/.venv/bin/ruff check policyengine_us/variables/gov/states/pa/tax/property/property_tax_or_rent_rebate
• /Users/daphnehansell/Documents/GitHub/policyengine-us/.venv/bin/python -m pytest policyengine_us/tests/test_parameter_files.py policyengine_us/tests/test_system_import.py

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (8cb60e7) to head (c4bffaf).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #8315   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         2    -1     
  Lines           63        33   -30     
=========================================
- Hits            63        33   -30     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.