Calculator Widget v61

[ovitrif]

The calculator OS home-screen widget work is being removed from #942 for now so the in-app calculator v61 work can be merged in time for 2.3.0.

Backup branch preserving the extracted OS widget work:

• ovi/calculator-os-widget-v61-backup

Related PRs:

• feat: calculator v61 redesign #942
• test: add android test lanes #943
• test: add calculator widget device tests #944
• fix: polish widgets foundation #946

Follow-up scope:

• Restore the calculator OS widget from the backup branch when design/product are ready.
• Decide whether the OS widget is display-only or opens Bitkit into the calculator flow.
• Keep OS widget state separate from in-app widget deletion if the OS widget returns.
• Recheck widget picker preview, Glance layout responsiveness, and locale-aware amount formatting.
• Add dedicated automated coverage in PRs restoring it, or their follow-ups.