Implement DDD refactoring phases 1-4 with domain layer and ubiquitous language

Phase 1-3: Domain Layer Foundation
- Add value objects: IdentityId, PermissionId, RelayId, WalletId, Nickname, NostrKeyPair
- Add rich domain entities: Identity, Permission, Relay with behavior
- Add domain events: IdentityCreated, IdentityRenamed, IdentitySelected, etc.
- Add repository interfaces for Identity, Permission, Relay
- Add infrastructure layer with repository implementations
- Add EncryptionService abstraction

Phase 4: Ubiquitous Language Cleanup
- Rename BrowserSyncData → EncryptedVault (encrypted vault storage)
- Rename BrowserSessionData → VaultSession (decrypted session state)
- Rename SignerMetaData → ExtensionSettings (extension configuration)
- Rename Identity_ENCRYPTED → StoredIdentity (storage DTO)
- Rename Identity_DECRYPTED → IdentityData (session DTO)
- Similar renames for Permission, Relay, NwcConnection, CashuMint
- Add backwards compatibility aliases with @deprecated markers

Test Coverage
- Add comprehensive tests for all value objects
- Add tests for domain entities and their behavior
- Add tests for domain events
- Fix PermissionChecker to prioritize kind-specific rules over blanket rules
- Fix pre-existing component test issues (IconButton, Pubkey)

All 113 tests pass. Both Chrome and Firefox builds succeed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

projects/common/src/lib/infrastructure/encryption/index.ts

@@ -0,0 +1,15 @@
+export {
+  isV1Context,
+  isV2Context,
+  createEncryptionContext,
+} from './encryption-context';
+export type {
+  EncryptionContext,
+  EncryptionContextV1,
+  EncryptionContextV2,
+} from './encryption-context';
+
+export {
+  EncryptionService,
+  createEncryptionService,
+} from './encryption.service';