[J2TeamNNL]

Summary

• Server Dashboard defaults to ⌥⇧⌘D and Query Insights to ⌥⇧⌘I.
• Both are listed and rebindable under Connections in Settings > Keyboard.
• The Database menu and the Actions pull-down draw both chords.
• A connection's menu on the connections strip lists both while the connection is live and browsing.
• The strip asks the hosting window's menu validation for that connection, so it lists what the menu bar would enable.
• Picking one selects the connection in its window and sends the menu bar's command there. The browsed database does not change.
• The strip's items draw no chord, since a chord runs on the window's connection.
• Agent mode menu validation is now an allowlist: only window, connection and session commands stay enabled. Before, about 40 commands acted on the hidden tabs, grid, sidebar or sheets.
• Agent mode has its own undo history; the window returns it while the mode is on.
• The grid's change manager always uses its own workspace's browse history.
• In Agent mode, ⌘W closes the database or connection instead of the hidden tab.
• The AI chat composer keeps its own typing undo history.
• Close Connection with Save now saves every tab's reachable work, and stays open when a tab's work can only be saved from that tab.
• Save at a close prompt waits for inspector edits to be written before closing.
• Docs: docs(shortcuts): Server Dashboard and Query Insights shortcuts and strip menu docs#146, to merge after this one.

Test plan

• WorkspaceRailServerToolTests: what the strip offers per context, item order and grouping, no chord, target and row.
• AgentModeWindowTests: a hosted connection's facts match the window's own in both modes; Close skips the hidden tab; Undo runs Agent mode's history, not the browse one.
• CommandActionsBulkCloseTests: connection Save refuses a background tab's grid edits it cannot reach.
• MenuContentModeParityTests: Agent mode dims New Table, Execute Query, Copy, Paste, Close Other Tabs, Backup and other hidden-content commands.
• MainMenuBuilderTests: Agent mode dims Server Dashboard, Query Insights, Users & Roles and ER Diagram.
• ConnectionActionsMenuResolverTests: each pull-down entry declares its menu-bar twin's shortcut.
• ChatComposerScrollViewTests: composer typing undoes in its own history.

Fixes #3936