Architecture: CryptoProvider DI + broadcast pattern for shared mutation hooks

[lamat1111]

@CassOnMars — two architectural questions for shared mutation hooks in @quilibrium/quorum-shared. Sibling to #65, #66.

1. CryptoProvider DI

Mobile uses NativeCryptoProvider ad-hoc at every space-crypto call site, plus a module-level singleton for DM crypto. When a shared hook needs crypto, it has to get a provider from somewhere.

Two paths:

• Context — CryptoContext + useCryptoProvider(), matching the existing StorageContext pattern. Shared hooks call useCryptoProvider() internally.
• Parameter — shared hooks accept cryptoProvider as an option. Cleaner separation, more boilerplate at each consumer.

2. Broadcast pattern for shared mutation hooks

When a shared mutation hook produces a new state, it has to broadcast a WS envelope. The send is platform-specific (broadcastSpaceUpdate on mobile, SpaceService.updateSpace on desktop).

Two paths:

• Return the envelope — caller dispatches via their platform's broadcast function.
• Callback — hook accepts onBroadcast(envelope) and calls it internally.

Issue #66 (channel reorder mutations not broadcasting) is a live instance of this question.

Or...

Defer shared mutation hooks entirely for now and migrate only read-query hooks until the patterns are clearer?