FIX - pagination issue when refreshing mastodon feed

[mltbnz]

Summary

Fixes two UX issues in the Mastodon feed refresh mechanism:

1. Refresh was incorrectly paginating instead of fetching the latest toots

Problem

Issue 1: Refresh Pagination Bug

When users pulled to refresh, the feed would load the next page of older toots instead of fetching the latest toots from the beginning. This happened because .fetchData was capturing lastId = state.toots.last?.id for both initial load and refresh actions.

Solution

1. Separate Refresh Logic from Pagination

Updated TootFeedFeature.swift:

• .refresh action: Sets isRefreshing = true (does NOT clear toots)
• .fetchData action: Always fetches with nil lastId to get latest toots
• .loadNextPage action: Continues to correctly use lastId for pagination

Before:

case .fetchData:
  return .run { [lastId = state.toots.last?.id] send in
    await send(.fetchDataResponse(Result { try await tootService.getToots(lastId) }))
  }

After:

case .refresh:
  state.isRefreshing = true
  return .send(.fetchData)

case .fetchData:
  return .run { send in
    await send(.fetchDataResponse(Result { try await tootService.getToots(nil) }))
  }

Test Coverage

✅ Initial Load Tests

• Verifies initial load fetches with nil lastId
• Ensures onAppear doesn't refetch when toots exist

✅ Refresh Tests

• Confirms refresh keeps toots visible during refresh
• Validates refresh fetches with nil lastId (not paginating)
• Ensures refresh doesn't use last toot ID

✅ Pagination Tests

• Verifies load next page uses lastId correctly
• Prevents loading when already loading
• Sets hasMore = false on empty response

✅ Error Handling Tests

• Handles fetch errors gracefully
• Stops refreshing on error

Behavior Changes

Action	Before	After
Initial load	Used lastId ❌	Fetches latest with nil ✅
Pull to refresh	Paginated from last toot ❌	Fetches latest, keeps content visible ✅
Load next page	Correctly paginated ✅	Still correctly paginated ✅

UX Improvements

Aspect	Before	After
Visual feedback	Flash of empty state	Smooth transition
Content visibility	Briefly hidden	Always visible
User experience	Jarring	Standard iOS pattern
Follows iOS HIG	No	Yes ✅

Testing

Run the test suite:

xcodebuild test -scheme CriticalMapsKit -destination 'platform=iOS Simulator,name=iPhone 17 Pro' -only-testing:MastodonFeedFeatureTests/TootFeedFeatureTests