feat: Add SOLID principles and TDD reference documentation

- Created solid.md to document the SOLID principles for clean code practices.
- Created tdd.md to outline Test Driven Development principles and practices.
- Added kana-rust-backend-best-practice.md as a reference guide for building a Rust backend using Axum and SeaORM.
- Established push-flow-convention.md to enforce pre-commit and pre-push hooks with versioning rules.
- Introduced AGENTS.md to provide guidance on best practices and available commands for Kilo.
- Configured kilo.json to include new skills and agents for enhanced functionality.
- Added lefthook.yml for managing git hooks to ensure code quality and adherence to conventions.

apps/infrastructure/src/persistence/cms/memory_repo.rs

@@ -175,7 +175,7 @@ impl MemoryRepository for MarkdownMemoryRepository {
 
     fn save(&self, memory_dir: &Path, memory: &Memory) -> Result<(), RepositoryError> {
         let path = Memory::path(memory_dir, &memory.name);
-        let parent = path.parent().unwrap();
+        let parent = path.parent().expect("memory path always has a parent directory");
         std::fs::create_dir_all(parent)?;
 
         let frontmatter = Self::build_frontmatter(memory);