feat: add knowledge management functionality with CRUD operations and database schema

- Implemented KnowledgeHandler for managing knowledge groups and items, including listing, creating, updating, and deleting operations.
- Added database migration scripts to create necessary tables for knowledge management, including knowledge_groups, knowledge_items, knowledge_parse_tasks, and knowledge_chunks_meta.
- Introduced prompt_rule_knowledge_groups table to associate prompt rules with knowledge groups.

server/internal/shared/retrieval/provider.go

@@ -0,0 +1,57 @@
+package retrieval
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"go.uber.org/zap"
+
+	"github.com/geo-platform/tenant-api/internal/shared/config"
+)
+
+var ErrNotConfigured = errors.New("retrieval provider is not configured")
+
+type Provider interface {
+	Validate() error
+	Embed(ctx context.Context, inputs []string) ([][]float64, error)
+	Rerank(ctx context.Context, query string, documents []string, topN int) ([]RerankResult, error)
+}
+
+type RerankResult struct {
+	Index          int
+	RelevanceScore float64
+	Text           string
+}
+
+func NewProvider(cfg config.RetrievalConfig, logger *zap.Logger) Provider {
+	provider := strings.ToLower(strings.TrimSpace(cfg.Provider))
+	switch provider {
+	case "", "disabled":
+		return disabledProvider{reason: "retrieval provider is disabled"}
+	case "siliconflow":
+		return NewSiliconFlowProvider(cfg, logger)
+	default:
+		return disabledProvider{reason: fmt.Sprintf("unsupported retrieval provider %q", cfg.Provider)}
+	}
+}
+
+type disabledProvider struct {
+	reason string
+}
+
+func (p disabledProvider) Validate() error {
+	if p.reason == "" {
+		p.reason = "missing retrieval configuration"
+	}
+	return fmt.Errorf("%w: %s", ErrNotConfigured, p.reason)
+}
+
+func (p disabledProvider) Embed(context.Context, []string) ([][]float64, error) {
+	return nil, p.Validate()
+}
+
+func (p disabledProvider) Rerank(context.Context, string, []string, int) ([]RerankResult, error) {
+	return nil, p.Validate()
+}