Not mergeable as-is — two real problems, both blocking:

1. Removes strictness flags from all three tsconfig files repo-wide (tsconfig.json, tsconfig.rollup.json, packages/react/tsconfig.json):

   -    "noImplicitAny":           true,
   -    "useUnknownInCatchVariables": true,

   This is a real regression in the codebase's type-safety guarantees, applying to every file in the SDK and the React package, not just the selector-memoization work this PR is about. This almost certainly exists to let the new code type-check without properly typing something (implicit anys or untyped catch bindings) rather than being an intentional, discussed policy change. Please restore both flags and fix whatever type errors that surfaces in the new code instead.

2. This branch is stale and would silently revert an already-merged fix. src/dashboard/transaction-history.ts's toIso8601/SPACE_SEPARATED_DATETIME helper (added by PR #406, "normalize space-separated indexer timestamps to ISO 8601 for Safari") is removed by this diff, along with its regression test in src/tests/transaction-history-crash.test.ts. GitHub shows this as a clean, conflict-free diff since the textual regions don't overlap — but merging as-is would reintroduce the Safari timestamp bug #406 just fixed. Please rebase onto current main and drop this reversion; the actual memoization work in transaction-history.ts's selectors doesn't need to touch asTimestamp/toIso8601 at all.

The core selector-memoization approach and the utils.ts amount-conversion caching look reasonable on a skim, but I'd like to see this rebased and with the tsconfig changes reverted before a full re-review.