feat(contexts): edit the menu when creating an application

[remko48]

The create application dialog gets a menu editor, so an application can be created with its menu in one go.

What changes

• MenuItemsEditor: an ordered list of menu items. Each item has an icon, a label and what it opens: a view, a page with widgets, a table or an external link. Only tables and views the user can manage are offered, since the server adds them to the application as resources. Picking a view or table fills in an empty label.
• Ordering and nesting: entries can be dragged by their handle, and every entry has move up/down buttons plus an indent button (top-level entries) or an outdent button (child entries), so the menu can be arranged with the keyboard. A parent moves together with its children; an entry with children cannot be indented; removing a parent moves its children to the top level instead of deleting them.
• Validation: the editor checks every entry with the same rules as the server (label, target, http/https link). Errors show once a row is left, and all of them on submit; an invalid menu blocks creating the application.
• ApplicationIcon: shows a material icon by name, used for the menu item icons.
• menuItems.js: the list operations of the editor, and turning its list into the API payload, including parentIndex for nested items.
• CreateContext: sends the menu with the new application.
• Deleting an application (existing behaviour on main, not caused by this stack): the delete removes the application first, inside a transaction that is retried, so it holds the write lock before it reads. On SQLite a delete that read first failed at once when another request wrote meanwhile.
• Tests: a Cypress component test covers the list operations, and a unit test covers the delete order.

Page target

The create dialog shows the dashboard item first. You can rename it and give it an icon, but you cannot remove it, move it, nest it or point it elsewhere, and no item can go above it, by button or by drag. It is sent as {targetType: 'page', targetId: null, technicalName: 'dashboard', label}, and the server resolves it to the new start page. A page item from the API passes through menuItems.js unchanged, without a validation error.

Tests:

• npm run test:component -- --spec cypress/component/menuItems.cy.js: 12 passing.
• New playwright/e2e/context-menu.spec.ts: creates an application in the UI and checks that the dashboard item comes first and is fixed, that the saved menu is Dashboard -> page <start page id> then the link, and that the application opens on its start page. 1 passed.
• context.spec.ts and context-navigation.spec.ts: 8 passed. One test needs the CI timeout of 120 s on the local instance.

The menu is not shown in the UI yet, so the check opens the start page by route. Prepared in the Conduction fork for porting upstream by @remko48. Prepared with Claude Code.

🖼️ Screenshots

🏚️ Before	🏡 After

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🏁 Checklist

• ⛑️ Tests (unit and/or integration) are included or not needed
• 🔙 Backport requests are created or not needed: /backport to stableX.X
• 📅 Milestone is set
• 🌸 PR title is meaningful (if it should be in the changelog: is it meaningful to users?)

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI