fix(opener): avoid blocking-runtime panic in reveal_item_in_dir

[cyclone-mind]

On Linux, reveal_items_in_dir opens a blocking zbus connection
(zbus::blocking::Connection::session()). The reveal_item_in_dir command runs
that synchronously on the async runtime's worker thread, which panics with
"Cannot start a runtime from within a runtime" — the JS promise then just hangs,
no rejection ever reaches the frontend.

Wrapped the call in tauri::async_runtime::spawn_blocking so it runs off the
async worker thread. Same fix the issue reporter already confirmed works as an
app-side workaround, just moved into the plugin so nobody has to hand-roll it.

Fixes #3552

Verified with cargo check / cargo fmt --check / cargo clippy on the opener
crate — all clean. Don't have a Linux box handy to reproduce the actual panic,
but the change is a direct port of the reporter's verified workaround.

Added a .changes entry per the repo's covector convention.

[github-actions]

Package Changes Through 8022336

There are 2 changes which include opener with patch, opener-js with patch

Planned Package Versions

The following package releases are the planned based on the context of changes in this pull request.

package	current	next
api-example	2.0.47	2.0.48
api-example-js	2.0.43	2.0.44
opener	2.5.5	2.5.6
opener-js	2.5.5	2.5.6

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