feat(linux): sidebar refresh, save to .sql, and visible storage errors

[datlechin]

• Sidebar: a Refresh Tables button; a failed read shows a banner with the reason and Retry until a read lands. A run that sends CREATE, ALTER, DROP, RENAME, ATTACH, DETACH, IMPORT, COMMIT/END or SELECT … INTO re-reads the table lists when it ends, through on_schema_changed. New invalidate_columns on the session catalog.
• Editor files: Save (Ctrl+S) and Save As (Ctrl+Shift+S) through gtk::FileDialog; Open SQL File gets Ctrl+O. The tab is named after its file with the path in the tooltip; the buffer's modified flag tracks unsaved text; the tab record keeps the file (optional field, no version bump). Closing the tab asks through Save Changes.
• Save Query loses Ctrl+Shift+S to Save As (GNOME's key for it) and keeps its menu item.
• Query history: an open failure holds a plain sentence (newer version, can't update, permission, disk full, damaged file); Query History, Saved Queries and Save Query show it in an alert; Preferences follows the history state live.
• Saved Queries: a read error shows an error page with Try Again, or keeps an already shown list.
• Show CREATE TABLE failure is an alert.
• Unreadable saved tabs keep a banner until Reset works; failing draft writes show one toast per run of failures.
• Name dialogs disable their button on an empty name and submit on Enter; new NameTaken storage error; Saved Queries shows its own toasts.
• Clear history says saved queries are kept; Ctrl+R reloads a table tab; history export items get an ellipsis; a failed Show in Files after export uses FileRevealer.
• The Preferences test window opens at a session window's size, removing the bottom-sheet warning from the gtk suite; a new test fails on warnings while showing the dialog.
• Tests changed on purpose: two sidebar tests now expect the banner, the history-gate test, the storage rename test (NameTaken), tab_keys_are_not_class_bindings_inside_the_tab (4 to 7 keys); the workspace CopyText test moved to a dialog test.