Switch from go-kit/log to log/slog

[fclairamb]

Summary

This PR migrates the logging implementation from the external github.com/fclairamb/go-log library (which wrapped go-kit/log) to Go's standard library log/slog for structured logging.

Changes Made

• Removed external dependencies: Eliminated github.com/fclairamb/go-log and github.com/go-kit/log from go.mod
• Updated logger types: Changed all log.Logger to *slog.Logger throughout the codebase
• Migrated logging calls: Updated all logging calls to use slog's structured logging API
• Updated tests: Converted test logging setup to use slog handlers
• Documentation updates: Updated README.md and CLAUDE.md to reflect the new logging approach
• Cleanup: Removed obsolete OpenCode.md file and added coverage.txt to .gitignore

Benefits

• Zero external dependencies for logging (uses only standard library)
• Better performance: slog is optimized and part of the standard library
• Improved structure: Native support for structured logging with key-value pairs
• Future-proof: Aligned with Go's recommended logging approach

Test Plan

• All existing tests pass with race detection enabled
• No linting issues (golangci-lint run returns 0 issues)
• Verified logging behavior in test output
• Confirmed backward compatibility with existing driver implementations

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.45%. Comparing base (4d23757) to head (106a816).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
handle_misc.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #595      +/-   ##
==========================================
+ Coverage   87.30%   87.45%   +0.15%     
==========================================
  Files          12       12              
  Lines        1772     1770       -2     
==========================================
+ Hits         1547     1548       +1     
+ Misses        151      148       -3     
  Partials       74       74              

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