Phase 68 — SQL Productivity

Based on Phase 67.

Query History: search by SQL, connection, schema, or execution detail; filter by successful/failed execution and connection.
Query History: copy SQL to clipboard, open a historical query in a new editor tab, and see matching result counts.
Saved SQL Queries: edit the name and SQL of existing saved queries, with validation before saving.
Saved SQL Queries: copy saved SQL without opening or executing it.
Saved query edits preserve stable IDs and are persisted through the existing storage mechanism.
No SQL is executed by browsing, editing, or copying history and saved queries.

Verification

Swift source was checked structurally, but full Xcode compilation and macOS UI testing are required.