feat: implement NIP-17 & NIP-44 v2 for Modern Direct Messages (#458)

* feat: implement NIP-17 & NIP-44 v2 for Modern Direct Messages

This commit introduces comprehensive support for NIP-17 (Private Direct Messages)
and NIP-44 v2 (Encrypted Payloads), establishing the modern standard for
secure messaging on Nostr.

Changes included:
- **NIP-17 Support**:
  - Added new Event Kinds: Seal (13), Direct Message (14), File Message (15), and Gift Wrap (1059).
  - Implemented `GiftWrapEventStrategy` to handle and validate incoming Gift Wrap events.
  - Added repository-level protections to block direct relay publication of inner events (Kinds 13, 14, 15), mandating they be encrypted inside a Gift Wrap.
- **NIP-44 v2 Crypto**:
  - Implemented `nip44Encrypt` and `nip44Decrypt` functions supporting ChaCha20, HKDF extraction/expansion, and MAC verification as per NIP-44 v2 specifications.
  - Added `validateNip44Payload` to ensure payloads adhere to the exact format requirements without needing to decrypt them.
- **Cleanup**:
  - Removed deprecated `encryptKind4Event` (legacy NIP-04 DM algorithm) from `event.ts`.
  - Updated `package.json` to declare NIPs 17 and 44 in `supportedNipExtensions`.
- **Tests**:
  - Added extensive unit tests across NIP-44 encryption logic, Event Strategies, and Message Handlers.
  - Resolved `sort-imports` ESLint violations in multiple handler specs.

* fix: address NIP-17/NIP-44 security review findings

- nip44: replace dead try/catch with explicit base64 regex + length%4 check
- gift-wrap: validate recipient p tag is a 64-char lowercase hex pubkey; fix error message
- mirroring worker: block inner event kinds (13/14/15) from being persisted directly

Author: CKodidela

package.json

@@ -11,11 +11,13 @@
     12,
     15,
     16,
+    17,
     20,
     22,
     28,
     33,
-    40
+    40,
+    44
   ],
   "supportedNipExtensions": [
     "11a"