feat: seedpgp v1.1.0 - BIP39 mnemonic PGP encryption tool

- Implement cv25519 PGP encryption/decryption
- Add Base45 encoding with CRC16 integrity checks
- Create SEEDPGP1 frame format for QR codes
- Support BIP39 passphrase flag indicator
- Add comprehensive test suite with Trezor BIP39 vectors
- 15 passing tests covering all core functionality

src/lib/types.ts

@@ -0,0 +1,14 @@
+export type SeedPgpPlaintext = {
+    v: 1;
+    t: "bip39";
+    w: string;
+    l: "en";
+    pp: 0 | 1;
+    fpr?: string[];
+};
+
+export type ParsedSeedPgpFrame = {
+    kind: "single";
+    crc16: string;
+    b45: string;
+};