feat(toolbar): make connection selectors navigational and move refresh/save to the trailing side

[datlechin]

What

Reworks the main window toolbar layout:

• The connection and database selectors (connectionGroup) are now an isNavigational group, so AppKit pins them to the leading side and keeps them out of normal overflow.
• The Refresh/Save group moves from before the centered title to after the flexible space, sitting on the trailing side next to the tab and query controls.
• Bumps toolbarIdentifier to com.TablePro.main.toolbar.v2. Reordering default items has no effect for existing users unless the identifier changes, because AppKit autosave restores the previously persisted layout. The bump forces a one-time reset to the new default arrangement.

Why

Groups navigation-style controls where macOS expects them and moves the action buttons next to the other action controls.

Notes

• Localizable.xcstrings picks up strings extracted from recent work (JSON import, toolbar, password sources).
• MainWindowToolbarValidationTests.toolbarIdentifierIsStable already expected .v2; the source bump makes it pass. Full MainWindowToolbarValidationTests suite passes.

Test plan

• MainWindowToolbarValidationTests passes
• swiftlint lint --strict clean on changed files
• Manual: existing install shows the new default toolbar order on first launch after update