Improved progress display

Previously, the progress bar updated only after completing an entire table.

For large tables such as LIBARC, this could make the application appear to have stopped responding.

Phase 10 updates the interface while rows are being exported.

PHASE21-NOTES.md

@@ -0,0 +1,17 @@
+# Phase 21 — SQL Query Plan Inspector
+
+Based on Phase 20.
+
+## Added
+- **Explain** button in SQL editor toolbar. Uses selected SQL when present, otherwise editor SQL.
+- Separate query-plan window showing MySQL `EXPLAIN` in table format or `EXPLAIN FORMAT=JSON`.
+- Shows optimizer plan columns in the existing native result grid; JSON format is selectable and copyable.
+- Displays diagnostic query duration and server errors.
+- Limits analysis to SELECT/WITH statements, does not run `EXPLAIN ANALYZE` (which executes the query).
+- Does not replace editor query results or add EXPLAIN to normal query history.
+
+## Notes
+- Requires an active connection and MySQL permissions to explain the query.
+- `EXPLAIN` gives estimated plans, not actual execution metrics.
+- Only a single SQL statement should be selected; multi-statement SQL is not supported in the plan inspector.
+- Not built in Xcode or tested against a live MySQL server in this environment.