Preserve copy-mode search text after Esc so n/N can repeat it

[sinharaksh1t]

In Herdr TUI 0.9.5 on macOS, pressing Esc after a copy-mode search clears the saved query and direction, so n/N can no longer repeat that search.

Reproduction:

1. Enter copy mode and search with /text, then Enter.
2. Press Esc to clear the search highlights.
3. Navigate to the top with g.
4. Press n or N. The previous search is no longer available.

Requested behavior: Esc should clear visible search highlights/selection while retaining the last search text and direction for n/N. A subsequent Esc, once highlights/selection are cleared, should still exit copy mode. This request concerns retaining the query within the current copy-mode session.

The v0.9.5 Esc handler explicitly clears search_query and search_direction: https://github.com/herdrdev/herdr/blob/v0.9.5/src/client/shell/copy_mode.rs#L112-L135

Could the remembered query/direction be kept separately from the visible highlight state, so clearing highlights does not disable repeat search?