✨ vanth/store, tests: Add persistent SQLite and in-memory store backends with CRUD operations

- Added `rusqlite` and `sqlx` dependencies to support SQLite backend functionality for the store.
- Implemented `Store` struct with backend switching between in-memory (`HashMap`) and SQLite-based storage.
- Added CRUD operations (`read`, `write`, `delete`) to the `Store` API with error handling.
- Created integration tests for SQLite store persistence and basic operations.

Cargo.toml

@@ -17,4 +17,7 @@ digest = "0.10.7"
 blake3 = { version = "1.8.2", features = ["traits-preview"] }
 quote = "1.0"
 syn = { version = "2.0", features = ["full"] }
-proc-macro2 = "1.0"
+proc-macro2 = "1.0"
+sqlx = "0.8.6"
+rusqlite = { version = "0.32.1", features = ["bundled"] }
+tempfile = "3.12.0"