Remove bootstrap guards from validation functions

This page is a capture in the next bucket of the product backlog — a pre-sprint idea, not yet pulled into a sprint as a story.

The codegen template sql_schema_table_create.mustache generates a bootstrap guard in every validation function:

if not exists (select 1 from X limit 1) then
    return p_value;
end if;

This pattern silently skips validation when the lookup table is empty, which was originally intended to avoid errors during initial population. However, correct population ordering in foundation_populate.sql makes these guards unnecessary. Worse, they mask real errors: if a lookup table is accidentally empty, inserts silently succeed with invalid data instead of failing loudly.

There are 20 instances across the codebase (16 in refdata, 1 in dq, 3 in iam).

Tasks:

• Update sql_schema_table_create.mustache to stop generating the bootstrap guard in the validation function template.
• Regenerate all affected SQL files.
• Remove bootstrap guards from any hand-written validation functions.
• Verify foundation_populate.sql ordering ensures all lookup tables are seeded before any dependent table triggers fire.
• Run full schema recreation and pgTAP tests to confirm nothing breaks.