feat(account): command handlers for account management (task 21)

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **Accounts commands** (PRD §6.4, PRD-v2 §P1.2, task 21): six application-layer command handlers (`add_account`, `update_account`, `delete_account`, `validate_account`, `export_accounts`, `import_accounts`) wired through the `CommandBus` builder. New driven ports `AccountCredentialStore`, `AccountValidator` (with `ValidationOutcome`) and `PassphraseCodec` keep handlers free of plugin / crypto dependencies. `KeyringAccountStore` adapter persists per-account passwords under `vortex-account-{id}` keyring entries; `AesGcmPbkdf2Codec` adapter implements the import / export bundle format using AES-256-GCM with a PBKDF2-HMAC-SHA256 200 000-iteration KDF, fresh per-call salt + nonce, header bound as AAD, and a `VORTACC` magic + version byte so tampered or downgraded bundles fail authentication. Domain events `AccountAdded`, `AccountUpdated`, `AccountDeleted`, `AccountValidated`, `AccountValidationFailed`, `AccountsImported`, `AccountsExported` published via `EventBus` and forwarded by the Tauri bridge as `account-*` browser events. Add rolls back the SQLite row when the keyring write fails so credentials never end up orphaned; import validates every entry up-front and skips `(service_name, username)` pairs already present without inserting partial state. Unblocks task 23 (Vue Accounts).
 - **Accounts persistence** (PRD §6.4, PRD-v2 §P1.1, task 20): SQLite `accounts` table (migration `m20260428_000006`) with `id` / `service_name` / `username` / `account_type` / `enabled` / `traffic_left` / `traffic_total` / `valid_until` / `last_validated` / `created_at` columns and a UNIQUE `(service_name, username)` index. New `AccountRepository` driven port (`save` / `find_by_id` / `list` / `list_by_service` / `delete`) and `SqliteAccountRepo` adapter with sea-orm entity + `from_domain` / `into_domain` converters. UNIQUE violations surface as `DomainError::AlreadyExists` instead of leaking storage errors. Domain `Account` aggregate gained `traffic_total`, `last_validated`, `created_at` fields and switched its identifier to `AccountId(String)` so generated account ids match the spec's `TEXT PRIMARY KEY`. `Account::credential_ref()` returns the `keyring://{service}/{username}` URI used to look up the password/token in the OS keychain — credentials are never persisted to SQLite. Unblocks tasks 21-25, 38, 51-56, 75-76.
 
 ## [0.2.0-beta] - 2026-04-27

src-tauri/Cargo.toml

@@ -56,6 +56,10 @@ hex = "0.4.3"
 tauri-plugin-dialog = "2.7.0"
 md-5 = "0.11.0"
 digest = "0.11.2"
+aes-gcm = "0.10.3"
+pbkdf2 = "0.13.0"
+hmac = "0.13.0"
+rand = "0.10.1"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"