Export: ODS meta block + header-row freeze/filter; flat CSV with aligned column names.

ODS sheets now carry a per-connection meta block (Connection / Transform
/ Left / Right) above the data; the header row anchors the freeze, the
auto-filter range, and the zebra striping. CSV stays a single flat
15-column table whose names match the ODS headers exactly.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/tui/screen_dashboard.cpp

@@ -299,7 +299,7 @@ Component Tui::BuildDashboardScreen() {
           {"e",      "explore"},
           {"a",      "analyze (verify + groups)"},
           {"h",      "help screen"},
-          {"x",      "export (CSV)"},
+          {"x",      "export"},
           {"PgUp",   "scroll up"},
           {"PgDn",   "scroll down"},
           {"Home",   "scroll top"},