Fix exception handling in select_all to raise errors instead of returning empty results

[cv]

Summary

Fixes #50 - select_all and related methods now properly raise DbException when ClickHouse returns error responses, instead of silently returning empty results.

Problem

When ClickHouse returns error responses with an 'exception' field in the JSON body (but without HTTP error codes or exception headers), the Response::Factory.response method was silently treating these as empty result sets instead of raising exceptions. This caused invalid queries like SELECT unknownFunction() to return [] instead of raising a proper error.

Solution

Added exception detection in Response::Factory.response before processing the response body. When the body is a Hash containing an 'exception' key, it now raises DbException with the error message from ClickHouse.

Key changes:

• lib/click_house/response/factory.rb - Added 4 lines to check for exception field and raise DbException
• Added comprehensive unit tests for Factory.response with error scenarios
• Added integration tests for select_all, select_one, and select_value error handling

Testing

• All 143 existing tests pass with no regressions ✅
• Added 5 new unit tests for Factory.response error handling ✅
• Added 5 new integration tests for query method error handling ✅
• Tested with Docker using ClickHouse 22.9 ✅
• RuboCop compliant ✅

Code Quality

• Minimal code change (4 lines)
• Follows existing error handling patterns (uses DbException)
• Well-documented with inline comments
• Consistent with codebase architecture
• No breaking changes (backward compatible)

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