feat: add stella-callgraph-node for JavaScript/TypeScript call graph extraction

- Implemented a new tool `stella-callgraph-node` that extracts call graphs from JavaScript/TypeScript projects using Babel AST.
- Added command-line interface with options for JSON output and help.
- Included functionality to analyze project structure, detect functions, and build call graphs.
- Created a package.json file for dependency management.

feat: introduce stella-callgraph-python for Python call graph extraction

- Developed `stella-callgraph-python` to extract call graphs from Python projects using AST analysis.
- Implemented command-line interface with options for JSON output and verbose logging.
- Added framework detection to identify popular web frameworks and their entry points.
- Created an AST analyzer to traverse Python code and extract function definitions and calls.
- Included requirements.txt for project dependencies.

chore: add framework detection for Python projects

- Implemented framework detection logic to identify frameworks like Flask, FastAPI, Django, and others based on project files and import patterns.
- Enhanced the AST analyzer to recognize entry points based on decorators and function definitions.

bench/reachability-benchmark/cases/go/grpc-sql/main_test.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func setupTestDB(t *testing.T) *sql.DB {
+	db, err := sql.Open("sqlite3", ":memory:")
+	if err != nil {
+		t.Fatalf("failed to open database: %v", err)
+	}
+
+	_, err = db.Exec(`
+		CREATE TABLE users (
+			id TEXT PRIMARY KEY,
+			name TEXT,
+			email TEXT
+		);
+		INSERT INTO users (id, name, email) VALUES ('1', 'Alice', 'alice@example.com');
+	`)
+	if err != nil {
+		t.Fatalf("failed to setup test data: %v", err)
+	}
+
+	return db
+}
+
+func TestGetUserSafe(t *testing.T) {
+	db := setupTestDB(t)
+	defer db.Close()
+
+	server := &userServer{db: db}
+	user, err := server.GetUserSafe(context.Background(), "1")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if user.Name != "Alice" {
+		t.Errorf("expected Alice, got %s", user.Name)
+	}
+}
+
+func TestGetUserNotFound(t *testing.T) {
+	db := setupTestDB(t)
+	defer db.Close()
+
+	server := &userServer{db: db}
+	_, err := server.GetUserSafe(context.Background(), "999")
+	if err == nil {
+		t.Error("expected error for non-existent user")
+	}
+}