Add comprehensive test suite and fix i18n/config issues

[alexander-acker]

Summary

This PR adds a comprehensive test suite covering core functionality and fixes several issues with internationalization and configuration management.

Key Changes

Test Suite (New Files)

• session-manager-lifecycle.test.ts: Tests for SessionManager lifecycle including session creation, continuation, deletion, and message handling
• store-actions.test.ts: Tests for Zustand store actions covering sessions, messages, trace steps, and UI state management
• database.test.ts: Tests for database initialization, CRUD operations, and schema creation
• config-store.test.ts: Tests for configuration store with provider presets and environment variable application
• memory-manager.test.ts: Tests for memory management including message history, search, and context management
• i18n-completeness.test.ts: Tests ensuring translation completeness between English and Chinese locales
• logger.test.ts: Tests for logging functionality
• credentials-store.test.ts: Tests for credentials storage and retrieval
• session-update.test.ts: Tests for session update utilities

Source Code Fixes

• config-store.ts: Fixed OpenRouter keyHint from Chinese to English ("Get from openrouter.ai/keys")
• session-manager.ts: Added cleanup of pending permissions when deleting a session to prevent memory leaks
• database.ts: Added FTS5 virtual table creation for memory search functionality
• MessageCard.tsx: Added missing useTranslation() hook for proper i18n support
• i18n locales: Added missing sidebar.deleteAllConfirm translation key in both English and Chinese
• Sidebar.tsx: Updated to use i18n translation key instead of hardcoded Chinese string

Notable Implementation Details

• All tests use Vitest with proper mocking of Electron, better-sqlite3, and electron-store modules
• Tests include edge cases like malformed JSON content handling and permission cleanup
• i18n tests verify completeness across locales and catch missing translation keys
• Database tests verify proper schema initialization and index creation
• Store tests validate state management patterns and cleanup operations

https://claude.ai/code/session_01EEkUmHuGJ1mJgB7mqoqTDK