feat(duckdb)!: Transpile Snowflake NORMAL to DuckDB

[fivetran-kwoodbeck]

Adds support for transpiling Snowflake's NORMAL function to DuckDB using the Box-Muller transform.

See the Jira task for full testing to confirm distribution similarity between Snowflake and transpiled version.

Changes:

• duckdb.py:
  • Add normal_sql() method to generate the transform. Uses templates and replace_placeholders due to unwieldily AST
  • Add NORMAL_TEMPLATE for Box-Muller formula: mean + stddev * sqrt(-2 * ln(u1)) * cos(2π * u2)
  • Add SEEDED_RANDOM_TEMPLATE for deterministic pseudo-random values

Behavior:
-- RANDOM() generator uses RANDOM()
-- Seeded generator uses HASH

[github-actions]

SQLGlot Integration Test Results

Comparing:

• this branch (sqlglot:feature/transpile-normal, sqlglot version: feature/transpile-normal)
• baseline (main, sqlglot version: 28.5.1.dev54)

⚠️ Limited to dialects: snowflake, duckdb

By Dialect

dialect	main	sqlglot:feature/transpile-normal	difference	links
duckdb -> duckdb	4003/4003 passed (100.0%)	4003/4003 passed (100.0%)	No change	full result / delta
snowflake -> duckdb	626/1085 passed (57.7%)	626/1085 passed (57.7%)	No change	full result / delta
snowflake -> snowflake	981/1085 passed (90.4%)	981/1085 passed (90.4%)	No change	full result / delta

Overall

main: 6173 total, 5610 passed (pass rate: 90.9%), sqlglot version: 28.5.1.dev54

sqlglot:feature/transpile-normal: 6173 total, 5610 passed (pass rate: 90.9%), sqlglot version: feature/transpile-normal

Difference: No change