Fix mask_amount_rounded type mismatch and add missing PII maskers to financial services

[puichinglee]

Summary

• Fix mask_amount_rounded runtime breakage: mask_amount_round returned STRING with a $ prefix (CONCAT('$', CAST(ROUND(...)))) but the underlying columns are DECIMAL/DOUBLE, causing type errors at query time. Renamed to mask_amount_rounded to match the canonical name in function_registry.json and changed the return type to RETURNS DECIMAL(18,2) with a clean ROUND(amount, -3) body.
• Add missing PII maskers: The LLM already tags Customer Email columns and routes them to mask_email, but the function definition didn't exist in financial_services.yaml. Added mask_email, mask_phone, and mask_address (ported from retail.yaml) plus Phone Number and Customer Address identifiers so all tagged PII columns have matching functions.
• Updated prompt_overlay to list the new functions and identifiers.

[puichinglee]

Test Results: Unit Tests

tests/test_industry_overlays.py::TestRetailContent::test_uses_hashing_for_names PASSED [ 77%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_loads_single_industry PASSED [ 78%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_loads_multiple_industries PASSED [ 78%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_case_insensitive PASSED [ 79%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_missing_industry_exits PASSED [ 80%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_returns_empty_for_empty_list PASSED [ 81%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_includes_group_templates PASSED [ 82%]
tests/test_industry_overlays.py::TestLoadIndustryOverlays::test_includes_access_patterns PASSED [ 83%]
tests/test_industry_overlays.py::TestBuildPromptWithIndustries::test_no_industries_produces_base_prompt PASSED [ 84%]
tests/test_industry_overlays.py::TestBuildPromptWithIndustries::test_industry_overlay_injected_before_my_tables PASSED [ 84%]
tests/test_industry_overlays.py::TestBuildPromptWithIndustries::test_multiple_industries_all_injected PASSED [ 85%]
tests/test_industry_overlays.py::TestBuildPromptWithIndustries::test_industry_with_mode_governance PASSED [ 86%]
tests/test_industry_overlays.py::TestBuildPromptWithIndustries::test_none_industries_no_overlay PASSED [ 87%]
tests/test_industry_overlays.py::TestBuildPromptWithBothOverlays::test_both_overlays_present PASSED [ 88%]
tests/test_industry_overlays.py::TestBuildPromptWithBothOverlays::test_country_appears_before_industry PASSED [ 89%]
tests/test_industry_overlays.py::TestBuildPromptWithBothOverlays::test_both_before_my_tables PASSED [ 89%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_loads_financial_hints PASSED [ 90%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_loads_healthcare_hints PASSED [ 91%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_loads_retail_hints PASSED [ 92%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_loads_function_categories PASSED [ 93%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_multi_industry_merges PASSED [ 94%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_missing_industry_skipped PASSED [ 94%]
tests/test_industry_overlays.py::TestLoadIndustryCategories::test_empty_list_returns_empty PASSED [ 95%]
tests/test_industry_overlays.py::TestInferColumnCategoriesWithIndustry::test_account_number_detected PASSED [ 96%]
tests/test_industry_overlays.py::TestInferColumnCategoriesWithIndustry::test_patient_id_detected PASSED [ 97%]
tests/test_industry_overlays.py::TestInferColumnCategoriesWithIndustry::test_loyalty_number_detected PASSED [ 98%]
tests/test_industry_overlays.py::TestInferColumnCategoriesWithIndustry::test_existing_us_patterns_still_work PASSED [ 99%]
tests/test_industry_overlays.py::TestFunctionExpectedCategoriesExtensionIndustry::test_industry_categories_can_be_merged PASSED [100%]

============================= 119 passed in 0.75s ==============================

Coverage

• test_validate_abac.py (44 tests) — all pass: validates ABAC config structure, tag policies, FGAC policies, SQL function parsing, condition matching, ACL groups
• test_industry_overlays.py (75 tests) — all pass: validates YAML integrity, identifier/function cross-refs, prompt overlay injection, category inference, function category merging

Key validations for this PR

• test_masking_functions_referenced_by_identifiers_exist[financial_services] — confirms all identifiers (including new Phone Number, Customer Address) reference functions that exist in the YAML
• test_masking_functions_have_required_fields[financial_services] — confirms mask_amount_rounded, mask_email, mask_phone, mask_address all have valid name/signature/body
• test_loads_function_categories — confirms industry overlay loading correctly maps functions to categories