GO-6331 objectstorestore remove on space leave

[requilence]

PR Description

TL;DR

Problem: When a user was kicked from a space (by another participant), the cleanup only removed ACL indexes via cleanACLIndexes() but left the space database files on disk. The space data was never fully removed.

Solution: Introduce proper space index lifecycle management tied to space mode transitions:

• OnSpaceModeChange hook triggers CloseSpaceIndex() when space enters Offloading mode
• DeleteSpaceIndex() permanently deletes the database files from filesystem and marks the proxy as deactivated

Why storeProxy: The proxy pattern was needed to safely handle the "deactivated but still referenced" state. After a space is deleted, existing code paths (like cross-space subscriptions or late callbacks) might still call SpaceIndex(deletedSpaceId). Without the proxy:

• Direct access would panic on nil
• Creating a new store would resurrect the deleted database via anystore.Open()

The proxy solves both: it returns sharedEmptyStore for deactivated spaces (safe empty results) and the removed flag prevents re-initialization even if Init() is called.

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Key Concepts

State	initialized	removed	Behavior
Uninitialized	false	false	Empty results, can Init()
Initialized	true	false	Real store operations
Closed	false	false	Empty results, can re-Init()
Deactivated	false	true	Empty results, Init() returns ErrSpaceRemoved

Flow

USER KICKED FROM SPACE:
1. Space mode → Offloading
2. OnSpaceModeChange() → CloseSpaceIndex()
3. storeProxy.initialized = false → delegates to sharedEmptyStore
4. DeleteSpaceIndex() → proxy.Deactivate() sets removed=true, deletes DB from disk

AFTER DELETION (safe access):
SpaceIndex(deletedId) → same proxy (in map) → removed=true → sharedEmptyStore → empty results, no DB recreation
Init() on deactivated proxy → returns ErrSpaceRemoved

Syncstatus optimization

• Added AllLoadedSpaceIds() which only returns spaces in ModeLoading state
• Excludes marketplace space and spaces being offloaded/deleted/joining
• Reduces unnecessary sync status queries for inactive spaces

[deff7]

why this is required? In order for subscriptions to work we need to re-run initial subscription query, not only register a callback