Feat/settings reset to defaults

[directorfloo]

Closes #438

Title: feat(settings): add "Reset to defaults" action with confirmation and toast

Summary
Adds a guarded "Reset to defaults" action on the Settings page that restores the persisted credence:settings payload to the defined defaults and shows a success toast. Uses the existing ConfirmDialog for destructive confirmation and restores focus to the trigger after close.

Why
Users need a one-click, guarded way to return settings to a known-good baseline (theme system, network public, address display short, toasts enabled, 5s auto-dismiss). Keeps behavior consistent with other destructive flows (ConfirmDialog + toast + focus restoration).

Key changes

• Implement resetToDefaults() and expose it on SettingsState in SettingsContext.tsx.
• Add a "Reset to defaults" action button to Settings.tsx that opens ConfirmDialog.
• On confirm: call resetToDefaults(), persist to credence:settings, show success toast "Settings reset to defaults.", and restore focus to the trigger button.
• Add/adjust unit tests validating reset behavior, persistence, toast, and focus restoration.

Files touched

• SettingsContext.tsx — add resetToDefaults() and extend SettingsState
• Settings.tsx — add Reset button, dialog wiring, returnFocusRef
• SettingsContext.test.tsx (and/or) src/pages/Settings.test.tsx — tests for reset flow

Implementation notes

• Uses existing storage key credence:settings (no new keys).
• resetToDefaults() sets in-memory values to defaultPersistedSettings then persists via existing save path.
• ConfirmDialog already implements focus trap and supports returnFocusRef.
• Toast uses existing toast API; message: "Settings reset to defaults."

Testing (local)
Unit:

• Run:

npx vitest run --config vite.config.ts src/context/SettingsContext.test.tsx
npx vitest run --config vite.config.ts src/pages/Settings.test.tsx

• Assert:
  • localStorage.getItem('credence:settings') equals defaultPersistedSettings JSON after confirm.
  • document.documentElement theme attribute reflects defaults.
  • Success toast shown with text "Settings reset to defaults."
  • Focus returns to the Reset button after dialog closes.

Manual:

1. Open Settings, change settings away from defaults.
2. Click "Reset to defaults".
3. Confirm.
4. Verify toast, settings equal defaults, and focus restored to the button.

Review checklist

• resetToDefaults() implemented and exported via SettingsState.
• Settings UI contains the Reset button and ConfirmDialog wiring.
• Toast fires with message "Settings reset to defaults."
• Focus restoration verified.
• Uses only credence:settings storage key.
• Tests added/updated and passing.
• TypeScript strict and lint checks pass.

Release notes

• UI: Added "Reset to defaults" button on Settings page (guarded by confirmation).

Optional follow-ups

• Add an "Undo" action on the toast to restore previous settings.
• Add telemetry for reset usage.

Want me to open the PR on GitHub (I’ll need your approval to push the branch + create the PR), or paste this as-is into a new PR for you?

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