Summary

Closes the SQL-injection audit sweep across the warehouse adapters and execution engine. Every untrusted-input format!-with-SQL site now refuses unsafe input rather than escaping it.

• rocky-bigquery/connector.rs — validate_identifier on catalog/schema/table in describe_table (the WHERE table_name = '...' literal is safe because the validator rejects single quotes), and on catalog/schema in list_tables (same class, found while there).
• rocky-databricks/loader.rs — format_target validates each segment and returns AdapterResult; the cloud URI passed to COPY INTO is checked against validate_cloud_uri (rejects ', \, \n, \r); the csv_delimiter: char is validated to keep the '<delim>' literal safe.
• rocky-snowflake/stage.rs + loader.rs — create_external_stage_sql, put_file_sql, file_format_clause refuse string-literal payloads with embedded quotes or backslashes; format_target validates target identifiers.
• rocky-engine/executor.rs — validate_identifier on model_name before the CREATE OR REPLACE TABLE format!; failed validation surfaces in the result's failed list.
• rocky-engine/profile.rs — generate_profile_sql returns Result and validates the table name and every column name.
• rocky-lang/lower.rs — unchanged. Token::Ident's lexer regex [a-zA-Z_][a-zA-Z0-9_]* is strictly tighter than validate_identifier, so every format! site there is safe by construction. Documented in the module header so a future reader doesn't have to re-derive it.

Threads validation at the SQL boundary the same way crates/rocky-databricks/src/{batch,dialect,permissions}.rs already do — no TableRef shape change, no newtype.

Test plan

• cargo test --workspace — all 30 test groups green
• cargo clippy --workspace --all-targets -- -D warnings — clean
• cargo fmt --check — clean
• Per-site rejection tests added (injection-bearing identifier, quote-in-URI, quote-in-CSV-delimiter, etc.)