Add coltypes parameter to MySQL.load for custom column types

[quinnj]

Summary

Fixes #225 - Allows overriding default SQL types when creating tables via MySQL.load().

• Add coltypes keyword argument to MySQL.load() that accepts a Dict mapping column names (as Symbols) to SQL type strings
• For example, users can now use LONGBLOB instead of BLOB for large binary data:

  MySQL.load(data, conn, "mytable"; coltypes=Dict(:photo => "LONGBLOB"))

Changes

• Add sqltype(T, coltypes, name) method to check coltypes dict first before falling back to default type mapping
• Pass coltypes through createtable() function
• Update docstring with documentation for the new parameter

Test plan

• Add test for coltypes override with LONGBLOB
• Verify column is created with correct type via SHOW COLUMNS
• Verify data roundtrips correctly

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.21%. Comparing base (cf5ce4f) to head (a5a01c1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #231      +/-   ##
==========================================
+ Coverage   63.17%   63.21%   +0.03%     
==========================================
  Files           9        9              
  Lines        1108     1109       +1     
==========================================
+ Hits          700      701       +1     
  Misses        408      408              

☔ 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.