refactor: stacks transaction summary LEA-3200

> Try out Leather build 62a7316 — [Extension build](https://github.com/leather-io/extension/actions/runs/17971146023), [Test report](https://leather-io.github.io/playwright-reports/refactor/transaction-summary), [Storybook](https://refactor/transaction-summary--65982789c7e2278518f189e7.chromatic.com), [Chromatic](https://www.chromatic.com/library?appId=65982789c7e2278518f189e7&branch=refactor/transaction-summary)<!-- Sticky Header Marker --> On the surface this might not seem like the highest priority refactor work, but it's responsible for some serious issues during transaction sending flows (and it has been frustrating me for a while). The mistake in the original implementation was pre-formatting all the data in some hooks, and passing a huge payload as route state through to the summary route. Entirely untyped and with inaccurate type casting . This led to false positive error screens leading users to believe their tx hasn't succeeded when in actual fact it has. All because of bugs that could easily be caught with the compiler.