IOS-5365 implement the async membership handling (simpler approach)

[requilence]

Updated membership data fetching to use middleware cache for faster app startup.

Problem

Middleware now returns cached membership/tiers data immediately (with noCache: false) instead of blocking on network calls. App startup was slow because we were forcing network calls with noCache: true.

Changes

Fast Startup

• Changed startSubscription() to use noCache: false (uses middleware in-memory cache)
• Initial load now instant - uses middleware's in-memory data

Event Handling

• Added membershipTiersUpdate event handling
• Both membershipUpdate and membershipTiersUpdate call getTiers() to refresh
• Service handles all filtering logic (test tiers, iOS compatibility)

Approach

• Simple and straightforward - reuses existing service filtering
• Events trigger RPC calls with noCache: false (fast, in-memory on middleware)
• Accepts duplicate getTiers() calls as inexpensive
• No architectural changes to storage or UI layers

Trade-offs

Compare with another PR with bigger refactoring #4111

Pros:

• Minimal code changes
• Reuses existing filtering logic in service
• Simple to understand and maintain

Cons:

• Extra RPC calls on events (though cheap - in-memory cache)
• Service called from both startup and event handlers

[claude]

Code Review

Bugs/Issues

MembershipStatusStorage.swift:68-75 - Missing error handling for membership status updates
When membershipTiersUpdate event is received and currentMembershipData is nil, the status won't be updated but no error is logged. This could hide issues during initial app states before any membership data is received.

MembershipStatusStorage.swift:38 - Race condition potential
noCache: false is now used during startSubscription(), but if middleware cache is empty on first launch, this could return stale/empty data while setupSubscription() hasn't received the first update yet. Consider logging if cache is empty or handling the empty state explicitly.

Best Practices

MembershipStatusStorage.swift:55 - Property not cleaned up
currentMembershipData is set to nil in stopSubscriptionAndClean() but should also be cleared when receiving membershipUpdate after it's used to prevent holding onto old data unnecessarily (line 70 already updates it, so this is technically handled, but the pattern is unclear).

Libraryfile:1 - Non-standard middleware version
Using branch name go-6337-make-tiersmembership-fetching-async instead of a version tag. This should be updated to a proper version/tag before merging to ensure reproducible builds.

MembershipCoordinatorModel.swift:29 - Missing initial state fetch
Added subscription to tiersPublisher but tiers property won't be populated until the publisher emits. Should initialize with membershipStatusStorage.currentTiers for immediate display.

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Summary: ⚠️ Minor Issues - Missing error handling, race condition potential, non-standard middleware version needs fixing before merge

[ignatovv]

we will not merge this pr to develop until there will be proper middleware veriosn

[ignatovv]

blocked until mw nightly build will arrive

[mgolovko]

Please disable "trim whitespace-only lines" in Xcode and rollback all this changes

[mgolovko]

properties first, methods next. Please move order back

[mgolovko]

Make alias in Service, MembershipStatus.swift file on the top. We don't use the middle names directly. There are big

[requilence]

closed in favor of #4111