Named session close blocks behind pending waits

Closing a named in-process session blocks behind a pending wait instead of interrupting it. `close_all()` interrupts the same wait promptly.

Observed on Windows at commit `2d5f8020ba6eb77b9c4da38892c2f6f200311b90`, while testing a new language binding against the existing Rust runtime.

### Reproduction

1. Start a named session with a program that stays alive.
2. Start a text-locator wait for text that will never appear, with a 5-second timeout.
3. While that wait is pending, close the same named session from another thread.
4. Check whether close completes within 2 seconds.

The close operation misses the 2-second deadline and remains blocked behind the wait. Repeating the scenario with `close_all()` completes promptly.

### Expected behavior

Closing one session should interrupt its pending wait and complete cleanup without waiting for the operation’s timeout, consistently with `close_all()`.

### Cause

[`SessionRegistry::execute`](https://github.com/microsoft/tui-test/blob/2d5f8020ba6eb77b9c4da38892c2f6f200311b90/crates/tui-test/src/runtime.rs#L459) holds the per-session generation mutex throughout operation execution, including waits.

Both `SessionRegistry::close()` and `execute(Operation::Close)` acquire that same mutex before reaching cleanup. They therefore cannot interrupt the operation holding it.

`close_all()` takes a different path: it calls `session.interrupt()` before closing sessions.

### Regression coverage

A regression test should establish that the wait has entered the runtime before invoking close, then verify:

- both named-close entrypoints interrupt the wait promptly
- the session is removed and its retained recording remains accessible
- an existing handle can reopen the named session
- unrelated sessions remain open

This is in the shared Rust runtime. JavaScript and Python use the same named-session path, although the reproduction above was exercised through the new binding.

Start in crates/tui-test/src/runtime.rs at SessionRegistry::execute and compare the named close paths with close_all(). Reproduce the pending text-locator wait on Windows, then add regression coverage for both named-close entrypoints, retained recordings, reopening, and unrelated sessions. Done means close interrupts promptly and all listed session behaviors remain intact.

Written by the indexing model from the issue text.