feat(backend): implement Phase 1 of Intelligence Layer Migration

- Add SQLite-based persistent memory storage (persistent.rs)
- Create memory persistence Tauri commands (memory_commands.rs)
- Add sqlx dependency to Cargo.toml for SQLite support
- Update memory module to export new persistent types
- Register memory commands in Tauri invoke handler
- Add comprehensive migration plan document

Phase 1 delivers:
- PersistentMemory struct with SQLite storage
- MemoryStoreState for Tauri state management
- 10 memory commands: init, store, get, search, delete,
  delete_all, stats, export, import, db_path
- Full-text search capability
- Cross-session memory retention

Reference: docs/plans/INTELLIGENCE-LAYER-MIGRATION.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src-tauri/src/lib.rs

@@ -18,6 +18,9 @@ mod browser;
 // Secure storage module for OS keyring/keychain
 mod secure_storage;
 
+// Memory commands for persistent storage
+mod memory_commands;
+
 use serde::Serialize;
 use serde_json::{json, Value};
 use std::fs;
@@ -1294,9 +1297,13 @@ pub fn run() {
     // Initialize browser state
     let browser_state = browser::commands::BrowserState::new();
 
+    // Initialize memory store state
+    let memory_state: memory_commands::MemoryStoreState = std::sync::Arc::new(tokio::sync::Mutex::new(None));
+
     tauri::Builder::default()
         .plugin(tauri_plugin_opener::init())
         .manage(browser_state)
+        .manage(memory_state)
         .invoke_handler(tauri::generate_handler![
             // OpenFang commands (new naming)
             openfang_status,
@@ -1372,7 +1379,18 @@ pub fn run() {
             secure_storage::secure_store_set,
             secure_storage::secure_store_get,
             secure_storage::secure_store_delete,
-            secure_storage::secure_store_is_available
+            secure_storage::secure_store_is_available,
+            // Memory persistence commands (Phase 1 Intelligence Layer Migration)
+            memory_commands::memory_init,
+            memory_commands::memory_store,
+            memory_commands::memory_get,
+            memory_commands::memory_search,
+            memory_commands::memory_delete,
+            memory_commands::memory_delete_all,
+            memory_commands::memory_stats,
+            memory_commands::memory_export,
+            memory_commands::memory_import,
+            memory_commands::memory_db_path
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");