feat: Phase 1 - Core API server with authentication

- Added database schema for users, api_keys, sync_state, change_log, and sync_config
- Implemented API key generation and validation with bcrypt hashing
- Created Chi-based REST API server with endpoints for:
  - Task CRUD operations (create, read, update, delete)
  - Task actions (complete, start, stop)
  - Tag management (list, add, remove)
  - Projects listing
  - Health check endpoint
- Added middleware for authentication and CORS
- Implemented change log tracking with triggers (key:value format)
- Added configurable change log retention (default 30 days)
- Created server CLI commands (opal server start, opal server keygen)
- Dependencies added: golang.org/x/crypto/bcrypt, github.com/go-chi/chi/v5

opal-task/internal/api/response.go

@@ -0,0 +1,39 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+)
+
+// Response represents a standard API response
+type Response struct {
+	Success bool        `json:"success"`
+	Data    interface{} `json:"data,omitempty"`
+	Error   string      `json:"error,omitempty"`
+}
+
+// JSON sends a JSON response
+func JSON(w http.ResponseWriter, status int, data interface{}) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+
+	response := Response{
+		Success: status >= 200 && status < 300,
+		Data:    data,
+	}
+
+	json.NewEncoder(w).Encode(response)
+}
+
+// Error sends an error response
+func Error(w http.ResponseWriter, status int, message string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+
+	response := Response{
+		Success: false,
+		Error:   message,
+	}
+
+	json.NewEncoder(w).Encode(response)
+}