feat(CalculationsDialog): add keyboard support and improve UX [UX-159]

[arina-gutuboe]

Implements UX-159

Description

Improves the Сalculations dialog so formulas can be built from the keyboard and the layout is easier to scan.

---

Key features

• Single-click to add data elements and operators (double-click is no longer required).
• Type operators (+, -, *, /, (, )) to append them after the selected item; numbers are still added by clicking.
• Move the highlighted formula item left/right with the arrow keys.
• Calculation name field moved to the top of the dialog.
• Operators and actions combined into one toolbar above a taller formula area.
• “Remove item” shown only when something is selected, with a delete icon.
• Validation result applied to the whole formula area (status border + message at the bottom).
• Modal width is fluid between a min and max based on window size.
• Formula items show full labels; truncation and hover tooltips are removed.
• Double-click no longer deletes items from the formula.

---

Deferred for future

• adding drag and drop between data elements field and formula field
• allow typing numbers

---

TODO

• Storybook updated

---

Screenshots

Before/after:

Validation output:

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud