Query history panel: no search, no clear-all, no deduplication

[eugene-mobile]

Problem

The query history panel has no search capability and no way to bulk-clear entries. With 35+ history items it becomes unwieldy to navigate.

Current limitations

1. No search/filter — to find a specific past query you must scroll through all entries
2. No "Clear all" button — each entry must be deleted individually with the X button
3. Duplicate entries — the same query run multiple times accumulates identical entries with no deduplication

Expected behaviour

• A search/filter input at the top of the history panel to filter by SQL content
• A "Clear all history" button or option
• Optionally: deduplicate identical consecutive queries (keep only the most recent run of each unique SQL)