[Feature] Create Staking migration widget (Fuse -> Celo savings)

[blueogin]

Short description of the new GoodWidget

Create a staking-migration-widget that helps users migrate their staked sG$ from Fuse staking to Celo savings.

The user action in the widget is approval only: user approves operator spend his erc20 sG$.
After approval, the widget sends the approval tx hash to the migration API, and the backend executes the migration.

Ship as @goodwidget/staking-migration-widget (React, React Native, Web Component), following @goodwidget/citizen-claim-widget.

Which repos and packages the AI should work with

Repo: GoodDollar/GoodWidget

• packages/staking-migration-widget/ (new) — widget, adapter, embed
• packages/core, packages/ui, packages/embed
• examples/storybook/, tests/widgets/staking-migration-widget/
• Pattern reference: packages/citizen-claim-widget/

External: GoodProtocol deployment.json (Fuse staking address);

Read first: AGENTS.md, ARCHITECTURE.md, docs/PACKAGING.md, docs/demo-environment.md, docs/architecture/theming-contract.md

UI implementation reference

Build a single card widget with clear migration progress.

During migrating, show these migration steps in the UI:

1. unstake
2. bridge sent
3. bridge received
4. stake

Each migration step must show status:

• Spinner while that step is running
• Done/check when completed
• Error indicator if failed

Only one active spinner at a time. Completed steps stay marked as done.

User flows, states and behaviours

1. Read user staked sG$ balance.
2. If balance is zero, show empty state and disable migration action.
3. User clicks approve/migrate.
4. Wallet approval tx opens on Fuse and confirms.
5. Widget calls migration API with approval tx hash.
6. Widget shows migration steps live (unstake → bridge sent → bridge received → stake).
7. On success, show completion state and final confirmation.
8. On failure, show which step failed and a clear message.

Required states:

• summary
• approval-pending
• approval-failed
• migrating
• success
• error
• wrong-network
• missing-config

User feedback requirements:

• Always show current step and what is happening now
• Keep completed steps visible for confidence
• On error, show both the failed step and reason
• Support retry from error state

Integration requirements:

• Host provides migrationApiBaseUrl, migrationOperator, optional migrationApiToken
• Keep provider-first architecture and existing package boundaries
• No new public theme targets without approval

Create the plan (keep this section in the issue body)

Create the plan

Based on the above description create an execution plan in a new sub-issue and preserve the original issue content unchanged.
Do not execute the plan until given instructions to do so.

Sub-issue requirements:

• Title format: [DRAFT][PLAN] <what issue is being planned>
• Type: Task
• Description must start with: <sub-issue title>
• Link the sub-issue back to this parent issue.

Instructions when creating the plan:

• Map relevant files that are too be used as reference from all repos mentioned
• import existing @GoodDollar packages
• Map new components that should be created. Assess when a new component should be created in the new savings widget package or made part of the reusable packages/ui

Plan specification required sections:

• Required states, flows, and behaviors
• Execution plan
• acceptance criteria
• human-reviewer checklist