fix: use Snowflake dialect for sqlglot SQL parsing

[elipollak]

Summary

get_statement_type() in query_manager/tools.py calls sqlglot.parse_one(sql_string) without specifying dialect="snowflake". This causes sqlglot to use its generic SQL parser, which fails on valid Snowflake-specific syntax:

• Colon-path notation (f.value:key::STRING) — used with LATERAL FLATTEN to extract nested fields
• COPY INTO statements (COPY statements incorrectly classified as "Unknown" instead of "Copy" #161)
• Other Snowflake-specific syntax (PARSE_JSON, OBJECT_CONSTRUCT, VARIANT casts, etc.)

When parsing fails, the statement is classified as Unknown, which is rejected unless users add Unknown: true to their permissions config — defeating the purpose of statement-type filtering.

Fix

One-line change: sqlglot.parse_one(sql_string, dialect="snowflake")

This was independently identified and fixed by @atvaccaro in the Notion fork: makenotion/snowflake-mcp@3d0192d, which also includes comprehensive test coverage for Snowflake-specific syntax parsing. Those tests would be a good addition here as well.

Verification

Adding the dialect parameter does not change classification of any standard statement types:

Statement	Default dialect	Snowflake dialect
SELECT	Select	Select
DROP TABLE	Drop	Drop
DELETE	Delete	Delete
INSERT	Insert	Insert
UPDATE	Update	Update
TRUNCATE	TruncateTable	TruncateTable
ALTER TABLE	Alter	Alter
CREATE TABLE	Create	Create
MERGE	Merge	Merge
GRANT	Grant	Grant
UNION	Union	Union
SELECT ... value:key	Unknown	Select
COPY INTO @stage	Unknown	Copy

Fixes #161

[bccolema]

Oooo, would this also separate SHOW out to its own setting option instead of bucketing it under command?!! If so, PLEASE APPROVE