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/firefox/src/app/common/data/firefox-sync-yes-handler.ts

@@ -1,12 +1,12 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import {
-  BrowserSyncData,
-  CashuMint_ENCRYPTED,
-  Identity_ENCRYPTED,
-  NwcConnection_ENCRYPTED,
-  Permission_ENCRYPTED,
+  EncryptedVault,
+  StoredCashuMint,
+  StoredIdentity,
+  StoredNwcConnection,
+  StoredPermission,
   BrowserSyncHandler,
-  Relay_ENCRYPTED,
+  StoredRelay,
 } from '@common';
 import browser from 'webextension-polyfill';
 
@@ -19,20 +19,20 @@ export class FirefoxSyncYesHandler extends BrowserSyncHandler {
     return await browser.storage.sync.get(null);
   }
 
-  async saveAndSetFullData(data: BrowserSyncData): Promise<void> {
+  async saveAndSetFullData(data: EncryptedVault): Promise<void> {
     await browser.storage.sync.set(data as Record<string, any>);
     this.setFullData(data);
   }
 
   async saveAndSetPartialData_Permissions(data: {
-    permissions: Permission_ENCRYPTED[];
+    permissions: StoredPermission[];
   }): Promise<void> {
     await browser.storage.sync.set(data);
     this.setPartialData_Permissions(data);
   }
 
   async saveAndSetPartialData_Identities(data: {
-    identities: Identity_ENCRYPTED[];
+    identities: StoredIdentity[];
   }): Promise<void> {
     await browser.storage.sync.set(data);
     this.setPartialData_Identities(data);
@@ -46,21 +46,21 @@ export class FirefoxSyncYesHandler extends BrowserSyncHandler {
   }
 
   async saveAndSetPartialData_Relays(data: {
-    relays: Relay_ENCRYPTED[];
+    relays: StoredRelay[];
   }): Promise<void> {
     await browser.storage.sync.set(data);
     this.setPartialData_Relays(data);
   }
 
   async saveAndSetPartialData_NwcConnections(data: {
-    nwcConnections: NwcConnection_ENCRYPTED[];
+    nwcConnections: StoredNwcConnection[];
   }): Promise<void> {
     await browser.storage.sync.set(data);
     this.setPartialData_NwcConnections(data);
   }
 
   async saveAndSetPartialData_CashuMints(data: {
-    cashuMints: CashuMint_ENCRYPTED[];
+    cashuMints: StoredCashuMint[];
   }): Promise<void> {
     await browser.storage.sync.set(data);
     this.setPartialData_CashuMints(data);