Extract shared service layer for sandbox, API key, and template operations

Moves business logic from API handlers into internal/service/ so that
both the REST API and the upcoming dashboard can share the same operations
without duplicating code. API handlers now delegate to the service layer
and only handle HTTP-specific concerns (request parsing, response formatting).

internal/service/apikey.go

@@ -0,0 +1,58 @@
+package service
+
+import (
+	"context"
+	"fmt"
+
+	"git.omukk.dev/wrenn/sandbox/internal/auth"
+	"git.omukk.dev/wrenn/sandbox/internal/db"
+	"git.omukk.dev/wrenn/sandbox/internal/id"
+)
+
+// APIKeyService provides API key operations shared between the REST API and the dashboard.
+type APIKeyService struct {
+	DB *db.Queries
+}
+
+// APIKeyCreateResult holds the result of creating an API key, including the
+// plaintext key which is only available at creation time.
+type APIKeyCreateResult struct {
+	Row       db.TeamApiKey
+	Plaintext string
+}
+
+// Create generates a new API key for the given team.
+func (s *APIKeyService) Create(ctx context.Context, teamID, userID, name string) (APIKeyCreateResult, error) {
+	if name == "" {
+		name = "Unnamed API Key"
+	}
+
+	plaintext, hash, err := auth.GenerateAPIKey()
+	if err != nil {
+		return APIKeyCreateResult{}, fmt.Errorf("generate key: %w", err)
+	}
+
+	row, err := s.DB.InsertAPIKey(ctx, db.InsertAPIKeyParams{
+		ID:        id.NewAPIKeyID(),
+		TeamID:    teamID,
+		Name:      name,
+		KeyHash:   hash,
+		KeyPrefix: auth.APIKeyPrefix(plaintext),
+		CreatedBy: userID,
+	})
+	if err != nil {
+		return APIKeyCreateResult{}, fmt.Errorf("insert key: %w", err)
+	}
+
+	return APIKeyCreateResult{Row: row, Plaintext: plaintext}, nil
+}
+
+// List returns all API keys belonging to the given team.
+func (s *APIKeyService) List(ctx context.Context, teamID string) ([]db.TeamApiKey, error) {
+	return s.DB.ListAPIKeysByTeam(ctx, teamID)
+}
+
+// Delete removes an API key by ID, scoped to the given team.
+func (s *APIKeyService) Delete(ctx context.Context, keyID, teamID string) error {
+	return s.DB.DeleteAPIKey(ctx, db.DeleteAPIKeyParams{ID: keyID, TeamID: teamID})
+}