Support direct DBInterface parameter binding

[quinnj]

Summary

• support DBInterface.execute(conn, sql, params) by preparing the statement for one execution
• retain the temporary statement on the returned cursor so bind buffers and the C handle remain valid through result consumption and explicit close
• add MySQL integration coverage for DML, nothing, last-row IDs, buffered and streaming reads, garbage collection, and date/time conversion

Root cause

MySQL.jl overrode DBInterface's connection-level fallback and explicitly rejected every non-empty parameter set, even though the package documentation described the call as supported. Calling the prepared-statement path alone was not sufficient because the returned cursor can outlive the convenience call. The cursor now owns the temporary statement for that lifetime.

Impact

Portable DBInterface code can use the same connection-level parameterized execution form with MySQL.jl, SQLite.jl, and Postgres.jl. Callers that execute the same SQL repeatedly should still use DBInterface.prepare to reuse the statement.

This completes the remaining behavior from #238. PR #239 already fixed nothing binding and transaction return values.

Validation

• focused issue reproduction passed against MySQL 8
• full suite passed on Julia 1.12.6: 217 tests
• full suite passed on Julia 1.10.11: 217 tests
• documentation build passed
• git diff --check passed

Closes #238

Co-authored by Codex

[codecov]

Codecov Report

❌ Patch coverage is 84.21053% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.68%. Comparing base (6144a81) to head (8103c44).

Files with missing lines	Patch %	Lines
src/prepare.jl	83.33%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #242      +/-   ##
==========================================
+ Coverage   71.50%   71.68%   +0.17%     
==========================================
  Files          10       10              
  Lines        1260     1275      +15     
==========================================
+ Hits          901      914      +13     
- Misses        359      361       +2     

☔ View full report in Codecov by Harness.
📢 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.