Add CREATE FOREIGN TABLE fixture with schema-qualified column type

[pyramation]

Summary

Adds a new SQL fixture for CREATE FOREIGN TABLE that tests a combination not covered by existing fixtures:

• Schema-qualified column type with typmod (pg_catalog.varchar(50))
• Common FDW option keys (schema_name, table_name)

The existing upstream/foreign_data.sql has extensive foreign table coverage but uses unqualified types like integer, text, date. This fixture adds coverage for qualified type names with type modifiers in foreign table column definitions.

Review & Testing Checklist for Human

• Verify the SQL syntax is valid and the fixture parses correctly (run pnpm test in packages/deparser)
• Confirm this pattern (pg_catalog.varchar(50) in a foreign table) isn't already covered elsewhere in the fixtures

Notes

• Link to Devin run: https://app.devin.ai/sessions/b20811a2d96c44a4a75fdf742aaa7978
• Requested by: Dan Lynch (@pyramation)

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring