Show secret phrase words with index prefix + 4×6 grid (24 words)

[ClidenorFilho]

Context

The wallet always generates a 24-word Secret Recovery Phrase. We want to:

• Show an index with a dot before each word (e.g., 1.hat, 2.word, …).
• Render the 24-word phrase in a 4-column × 6-row grid.

Scope

• UI only: prepend {index}. to each displayed word.
• Layout: force 4 columns × 6 rows for 24 words.
• Copy behavior: clicking Copy must copy the real 24-word phrase (no indices).

Requirements

• Each cell shows i + 1 followed by . before the word (e.g., 1.hat).
• Use a 4×6 grid for 24 words; input mode remains editable; adornment shows the index.
• Copy feature copies mnemonicWords.join(" ") (no indices).

Implementation Notes

• Updated packages/app-extension/src/components/common/Account/MnemonicInput.tsx

  • Components touched: MnemonicInputFields, _ReadonlyMnemonicTable
  • TextField.InputProps.startAdornment now renders ${i + 1}.
  • Grid column size set to xs={3} when mnemonicWords.length === 24 (4 columns).

Risks

• Potential layout tightness on very narrow viewports; verify spacing of the adornment.

Linked Issue

Closes #4379

Labels

type: feature · area: ui · priority: medium · wallet/onboarding