[fix] Avoid create schema

[muir]

Avoid issuing CREATE SCHEMA / CREATE DATABASE when they already exist
This avoids potential permissions issues.

[codecov]

Codecov Report

❌ Patch coverage is 76.27119% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.74%. Comparing base (2963391) to head (6807496).

Files with missing lines	Patch %	Lines
lssinglestore/singlestore.go	69.56%	4 Missing and 3 partials ⚠️
lspostgres/postgres.go	83.33%	3 Missing and 1 partial ⚠️
lsmysql/mysql.go	75.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #362      +/-   ##
==========================================
- Coverage   81.90%   81.74%   -0.16%     
==========================================
  Files          16       16              
  Lines        1752     1786      +34     
==========================================
+ Hits         1435     1460      +25     
- Misses        195      200       +5     
- Partials      122      126       +4     

Flag	Coverage Δ
go_tests	19.70% <5.08%> (-0.33%)	⬇️
mysql_tests	47.91% <15.25%> (-0.60%)	⬇️
pg_tests	51.83% <55.55%> (-0.06%)	⬇️
singlestore_tests	44.75% <27.11%> (-0.25%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull request overview

This PR aims to avoid issuing CREATE SCHEMA / CREATE DATABASE when the schema already exists, to reduce the chance of hitting permission errors in environments where the user can use an existing schema but cannot create it.

Changes:

• SingleStore/MySQL: query information_schema.schemata before attempting schema creation.
• Postgres: query information_schema.schemata before attempting schema creation, and refactor tracking-table parsing to return both raw and quoted schema names.
• SingleStore: adjust tracking table qualification to use a separately-quoted schema component.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
lssinglestore/singlestore.go	Adds schema existence check and adjusts schema/table quoting for the tracking table.
lspostgres/postgres.go	Adds schema existence check and refactors tracking table parsing to separate raw vs quoted identifiers.
lsmysql/mysql.go	Adds schema existence check before attempting CREATE SCHEMA.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.