Security: upgrade nostr stack 0.40->0.45 clearing 11 RustSec advisories

- nostr 0.40.0 -> 0.45.3, nostr-sdk 0.40.0 -> 0.45.2 (secp256k1 0.30)
- fixes RUSTSEC-2026-0216/0219/0224/0225/0226/0227/0228/0229/0230/0231/0232
  incl. forged-event signature-bypass and NIP-46 credential Debug leak
- NIP-42 auth now explicit: SignerAuthenticator on every client path
- EventBuilder::sign -> finalize_async; nip44 encrypt supplies random nonce
- feed/signer receive loops moved to stream_events (receiver opens before
  the signer announces, preserving the ordering fix)
- relay-pool replaced by in-SDK relay/gossip; try_connect().timeout()
- tests: malformed NIP-44 payload rejection + secret-leak regression
- suite: 115 backend tests green (113 preserved + 2 new); frontend untouched

Cargo.toml

@@ -4,8 +4,8 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-nostr = { version = "0.40", features = ["nip44", "nip46"] }
-nostr-sdk = { version = "0.40", features = ["nip44", "nip98"] }
+nostr = { version = "0.45", features = ["nip44", "nip98"] }
+nostr-sdk = "0.45"
 tokio = { version = "1", features = ["full"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"