## Summary

When opening the text finder (`text_finder::Toggle`), pre-populate its
query the same way project search already seeds itself. Previously
`seed_query` only asked the active editor for the word under the cursor,
so opening the text finder from a project search tab or a focused buffer
search bar started empty.

`seed_query` now tries these sources in priority order:

1. **Active project search** — its current query
(`ProjectSearchView::search_query_text`).
2. **Focused buffer search bar** — its query, reusing project search's
existing `buffer_search_query` helper (promoted from private to
`pub(crate)` so there's one source of truth rather than a copy).
3. **Word under the cursor** — the existing `query_suggestion` fallback,
still honoring the `seed_search_query_from_cursor` setting.

This mirrors how project search is fed from the buffer search bar
(`existing_or_new_search`), keeping the seeding behavior consistent
across the three search surfaces.

## Testing

- Manual: open project search with a query → toggle text finder → query
carries over; cmd+f with a query focused → toggle text finder → query
carries over; otherwise the word under the cursor seeds it as before.

Release Notes:

- Improved text finder to pre-fill its query from the active project
search or buffer search

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Co-authored-by: ozacod <ozacod@users.noreply.github.com>
Co-authored-by: Yara 🏳️‍⚧️ <git@yara.blue>