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/domain/events/identity-events.ts

@@ -0,0 +1,74 @@
+import { DomainEvent } from './domain-event';
+
+/**
+ * Event raised when a new identity is created.
+ */
+export class IdentityCreated extends DomainEvent {
+  readonly eventType = 'identity.created';
+
+  constructor(
+    readonly identityId: string,
+    readonly publicKey: string,
+    readonly nickname: string
+  ) {
+    super();
+  }
+}
+
+/**
+ * Event raised when an identity is renamed.
+ */
+export class IdentityRenamed extends DomainEvent {
+  readonly eventType = 'identity.renamed';
+
+  constructor(
+    readonly identityId: string,
+    readonly oldNickname: string,
+    readonly newNickname: string
+  ) {
+    super();
+  }
+}
+
+/**
+ * Event raised when an identity is selected (made active).
+ */
+export class IdentitySelected extends DomainEvent {
+  readonly eventType = 'identity.selected';
+
+  constructor(
+    readonly identityId: string,
+    readonly previousIdentityId: string | null
+  ) {
+    super();
+  }
+}
+
+/**
+ * Event raised when an identity signs an event.
+ */
+export class IdentitySigned extends DomainEvent {
+  readonly eventType = 'identity.signed';
+
+  constructor(
+    readonly identityId: string,
+    readonly eventKind: number,
+    readonly signedEventId: string
+  ) {
+    super();
+  }
+}
+
+/**
+ * Event raised when an identity is deleted.
+ */
+export class IdentityDeleted extends DomainEvent {
+  readonly eventType = 'identity.deleted';
+
+  constructor(
+    readonly identityId: string,
+    readonly publicKey: string
+  ) {
+    super();
+  }
+}