[tompro]

Summary

Expose the existing payday_node_lnd::lnd::create_client constructor publicly so advanced RPC callers reuse Payday's connection/TLS policy instead of duplicating the three-way LndConfig match.

This is a requested cleanup for https://github.com/The-Bitcoin-Company/tbc-rust/pull/652, which will replace its duplicated constructor with this function.

• Constructor body, TLS behavior, and dependencies are unchanged; visibility changes from pub(crate) to pub.
• Document configuration/TLS semantics, caller-owned caching/timeouts, lazy reachability/authentication and required error sanitization.
• Add an external doctest that type-checks the public future without polling it or performing network I/O.

Validation

Using the TBC Rust Nix shell:

• cargo test --locked -p payday_node_lnd: 20 unit tests + 1 doctest passed.
• All-target check and all-target/all-feature Clippy (-D warnings) for payday_node_lnd passed.
• Dedicated doctests, changed-file rustfmt check, and git diff --check passed.
• No live node/TLS tests. Constructor body was verified unchanged against the base commit.