Add a purposeful subset of Amethyst-style relay categories (not a full clone):
- App-local 'Local relays' (never published; added to reads+writes)
- App-local 'Blocked relays' (excluded from every read/write)
- src/lib/relays.ts: resolveRelays()/useRelays() + URL normalisation
- NostrProvider req/event routers go through resolveRelays (blocklist applied)
- RelayListManager: Local/Blocked editors; NIP-65 save now preserves the new
lists instead of overwriting relayMetadata
Deliberately omitted (documented in AGENTS.md): KeyPackage (10051, no MLS
consumer) and proxy/broadcast/private-home (no such discovery model here).
Follow-up noted: a few hooks still read config.relayMetadata.relays directly.
