Ramp remove quote polling

[georgeweiler]

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Breaking API/behavior change for quote refresh timing; consumers must update to explicitly refetch quotes and could see stale quotes if they don’t.

Overview
Removes automatic 15-second quote polling from RampsController and replaces it with a one-shot fetchQuotesForSelection() call that fetches quotes once for the currently selected token/provider/payment method while keeping the existing auto-selection/selection-preservation behavior.

Cleans up related lifecycle logic by deleting stopQuotePolling(), interval state, and dependency-triggered polling restarts in setSelectedProvider/setSelectedToken/setSelectedPaymentMethod, and updates tests + changelog to reflect the new API and widget URL sync behavior.

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