feat: add option to group all connection tabs in one window

[datlechin]

Summary

• Adds Settings > Tabs > Group all connections in one window toggle (default: off)
• When enabled, all native macOS window tabs share one tab group regardless of connection, instead of separate windows per connection
• Fixes multiple related bugs: cross-connection tab destruction on database switch, connection failure nuking all windows, tab title flashing to "SQL Query" after query execution, crash on window close (NSWindowStackController assertion)

Changes

New feature

• TabSettings.groupAllConnectionTabs — new boolean setting with Codable backward compatibility
• TabbingIdentifierResolver — returns shared "com.TablePro.main" when groupAll is ON
• AppDelegate+WindowConfig — normalizes all existing windows' tabbingIdentifier when groupAll is ON; skips orderOut for windows in active tab groups to prevent NSWindowStackController crash
• ConnectionSwitcherPopover — uses openNativeTab path when groupAll is ON instead of forcing separate window
• AppDelegate+ConnectionHandler / AppDelegate+FileOpen — skip allowsAutomaticWindowTabbing = false when groupAll is ON
• Settings UI toggle + docs + CHANGELOG

Bug fixes (apply regardless of groupAll setting)

• closeSiblingNativeWindows() now filters by connectionId — prevents closing other connections' tabs during database switch
• openTableTab sibling search now filters by connection ownership — prevents false-positive matches across connections with same table name
• openPreviewTab now reuses non-preview table tabs with no active work + empty query tabs — prevents orphaned "SQL Query" tabs
• WelcomeViewModel / ConnectionFormView connection failure handlers now close only the failing connection's windows via WindowLifecycleMonitor, not all main windows
• connectFromDock failure handler scoped to failing connection's windows
• executeQueryInternal / applyMultiStatementResults preserve tableName for table tabs instead of re-extracting from SQL (fixes title fallback to "SQL Query" when regex fails on schema-qualified identifiers)
• configureWindow in MainContentView respects groupAllConnectionTabs for tabbingIdentifier

Tests

• 2 new tests for TabbingIdentifierResolver.resolve(groupAllConnections: true)

Test plan

• Enable "Group all connections in one window" in Settings > Tabs
• Connect to db1, then open db2 via connection switcher — both should appear as tabs in the same window
• Click tables in db2 sidebar — title should show table name (not "SQL Query")
• Navigate tables with keyboard up/down — title should always show the correct table name
• Make unsaved changes, click another table — should open new tab (not replace)
• Switch database via Cmd+K — should only close tabs from current connection, not others
• Close a connection that fails during query — should not close other connections' tabs
• Disable the setting — connections should open in separate windows again
• Open connection via deeplink — should respect the groupAll setting