Fix int64/uint64 type inference to use BIGINT instead of INTEGER

[vikrantpuppala]

Summary

• Fixes a bug where int64 and uint64 values were incorrectly mapped to SqlInteger instead of SqlBigInt
• Fixes data loss issue where int64 was converted using strconv.Itoa(int(value)) which truncates large values
• Adds safe type assertion in convertNamedValuesToSparkParams to prevent panic when Parameter.Value is not a string

Problem

When inserting int64/uint64 values into BIGINT columns, the driver was sending them with type INTEGER instead of BIGINT, causing the server to reject large values with error:

[INVALID_PARAMETER_MARKER_VALUE.INVALID_VALUE_FOR_DATA_TYPE] An invalid parameter mapping was provided: 
the value '1311768467463790320' for parameter 'null' cannot be cast to INT because it is malformed.

Test plan

• Added unit tests for int64/uint64 type inference (TestParameter_BigInt)
• Verified large int64 values are correctly inserted and retrieved from BIGINT columns
• All existing parameter tests pass

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This pull request fixes a critical bug where int64 and uint64 values were incorrectly mapped to SqlInteger (INT) instead of SqlBigInt (BIGINT), causing data truncation and server rejection of large values.

Changes:

• Fixed int64 type inference to use strconv.FormatInt and SqlBigInt instead of lossy int casting
• Fixed uint64 type inference to use SqlBigInt and removed redundant type cast
• Added defensive type assertion in convertNamedValuesToSparkParams to handle non-string Parameter values

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
parameters.go	Fixed int64/uint64 type mappings from INTEGER to BIGINT and corrected value conversion to prevent data loss; added safe type handling for Parameter.Value
parameter_test.go	Added comprehensive test suite covering int64/uint64 BIGINT inference, edge cases (min/max values), explicit Parameter handling, and int32 preservation

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[vikrantpuppala]

Closing in favor of #316 which includes this fix along with the float64 fix