Apply ruff linting fixes across the codebase

[Edwardvaneechoud]

• Fixed 229 linting errors using ruff check --fix and --unsafe-fixes
• Manually fixed all 16 issues in flowfile_frame/flow_frame.py (file with most issues)
  • Added proper exception chaining (from e) for B904 errors
  • Fixed line-too-long errors by breaking strings across lines
  • Fixed isinstance calls to use modern PEP 604 syntax (X | Y)
• Auto-fixed trailing whitespace, unused variables, and other minor issues
• Reduced total errors from 370 to 141 (61% improvement)

In general: when executing SQL that incorporates user input, restrict the allowed shape of the query and/or use parameterized queries. Since this endpoint is for validating arbitrary database settings and is explicitly designed to accept a user‑provided query, we cannot simply switch to bound parameters here. Instead, we should harden the validation to ensure the query is strictly a single read‑only SELECT (optionally with CTEs), with no additional statements or dangerous keywords, before passing it to text().

Best targeted fix without changing existing functionality: add an explicit, conservative check in get_query_columns that enforces the same invariants that validate_sql_query is supposed to guarantee, but in a way that is locally visible and robust:

• Normalize the query (strip, uppercase, collapse whitespace) and reuse _is_select_query to ensure it is a SELECT or CTE leading to SELECT.
• Explicitly reject:
  • any semicolons (;) to prevent multiple statements;
  • common data‑modification or DDL keywords (e.g. INSERT, UPDATE, DELETE, DROP, ALTER, TRUNCATE, CREATE, MERGE, EXEC, CALL, GRANT, REVOKE), outside of string literals (simple heuristic: just banning these tokens in the normalized query).
• If the query fails these checks, raise a dedicated UnsafeSQLError (or, since that type isn’t defined in the shown snippet, a ValueError with a clear message) before calling text().

This keeps existing API behavior (user can still supply a query), but ensures that only safe, single‑statement, read‑only queries enter connection.execute(). The changes are confined to flowfile_core/flowfile_core/flowfile/sources/external_sources/sql_source/sql_source.py within the shown region, and only add a small pre‑execution check; no existing imports need to change.

Concretely:

• In get_query_columns, after validate_sql_query(query_text) and before with engine.connect(), add:
  • normalization of query_text,
  • a call to _is_select_query,
  • a small list of disallowed tokens and a check for them,
  • raising an exception if the query is not clearly a safe SELECT.
• We reuse the existing _is_select_query helper, so no new helper definitions are required.
• No changes are needed in routes.py.

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