Add TLS and mTLS support

[HTHou]

Summary

Add TLS and mTLS support for the Go client session transport path.

Changes

• Add client.TLSConfig with CA trust loading and optional client certificate/key loading.
• Use TLS transport when TLSConfig is present for standalone sessions, cluster sessions, reconnects, and session pools.
• Document TLS/mTLS usage in English and Chinese READMEs.
• Add unit coverage for TLS config cloning, CA/client certificate loading, and client cert/key validation.

Validation

• git diff --cached --check
• go test $(go list ./... | grep -v '/test/e2e')\n\nE2E tests were not run locally because they require an IoTDB service/DNS entry (iotdb) in the test environment.

[Copilot]

Pull request overview

Adds TLS and mutual TLS (mTLS) support to the Go client’s Thrift transport creation path, allowing sessions, cluster sessions, and session pools to connect securely using configured CA trust and optional client certificates.

Changes:

• Introduces client.TLSConfig plus helpers to build a *tls.Config from CA/client cert/key files.
• Routes session and cluster session transport creation through a shared newTransport(..., tlsConfig) that can create either plain or TLS transports.
• Documents TLS/mTLS usage in English and Chinese READMEs and adds unit tests for TLS config behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
README.md	Documents TLS/mTLS configuration and provides a usage snippet.
README_ZH.md	Adds the same TLS/mTLS guidance in Chinese.
client/tls.go	Implements TLSConfig, TLS config building, and TLS-capable transport creation.
client/tls_test.go	Adds unit tests for cloning base TLS config, loading CA/cert/key files, and cert/key validation.
client/sessionpool.go	Plumbs TLSConfig through pool config into session/cluster configs.
client/session.go	Switches session and cluster session transport initialization to use the TLS-capable transport helper.

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.