Thread ctx through auth middleware DB lookups

The auth middleware's m.db.Preload + m.db.First calls were running without
ctx, so on cache miss the resulting SQL queries appeared as orphan
gorm.Query / gorm.Row spans in Jaeger. Now they nest under the parent
HTTP request span like every other repo call.

This was the last orphaned-SQL source on the request hot path. Combined
with the seven service migrations, every authenticated API call now
produces a fully-nested flame graph: HTTP → auth-token-lookup (cache hit)
or HTTP → auth-token-SQL (cache miss) → service → service-SQL.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/middleware/auth.go

@@ -104,7 +104,7 @@ func (m *AuthMiddleware) TokenAuth() echo.MiddlewareFunc {
 			}
 
 			// Cache miss - look up token in database
-			user, authToken, err := m.getUserFromDatabaseWithToken(token)
+			user, authToken, err := m.getUserFromDatabaseWithToken(c.Request().Context(), token)
 			if err != nil {
 				log.Debug().Err(err).Str("token", truncateToken(token)).Msg("Token authentication failed")
 				return apperrors.Unauthorized("error.invalid_token")
@@ -148,7 +148,7 @@ func (m *AuthMiddleware) OptionalTokenAuth() echo.MiddlewareFunc {
 			}
 
 			// Try database
-			user, authToken, err := m.getUserFromDatabaseWithToken(token)
+			user, authToken, err := m.getUserFromDatabaseWithToken(c.Request().Context(), token)
 			if err == nil && !m.isTokenExpired(authToken.Created) {
 				m.cacheTokenInfo(c.Request().Context(), token, user.ID, authToken.Created)
 				c.Set(AuthUserKey, user)
@@ -224,7 +224,7 @@ func (m *AuthMiddleware) getUserFromCache(ctx context.Context, token string) (*m
 
 	// In-memory cache miss — fetch from database
 	var user models.User
-	if err := m.db.First(&user, userID).Error; err != nil {
+	if err := m.db.WithContext(ctx).First(&user, userID).Error; err != nil {
 		// User was deleted - invalidate caches
 		m.cache.InvalidateAuthToken(ctx, token)
 		return nil, err
@@ -242,10 +242,11 @@ func (m *AuthMiddleware) getUserFromCache(ctx context.Context, token string) (*m
 }
 
 // getUserFromDatabaseWithToken looks up the token in the database and returns
-// both the user and the auth token record (for expiry checking).
-func (m *AuthMiddleware) getUserFromDatabaseWithToken(token string) (*models.User, *models.AuthToken, error) {
+// both the user and the auth token record (for expiry checking). The ctx is
+// threaded into the GORM session so the SQL span attaches to the request trace.
+func (m *AuthMiddleware) getUserFromDatabaseWithToken(ctx context.Context, token string) (*models.User, *models.AuthToken, error) {
 	var authToken models.AuthToken
-	if err := m.db.Preload("User").Where("key = ?", token).First(&authToken).Error; err != nil {
+	if err := m.db.WithContext(ctx).Preload("User").Where("key = ?", token).First(&authToken).Error; err != nil {
 		return nil, nil, fmt.Errorf("token not found")
 	}
 
@@ -262,8 +263,8 @@ func (m *AuthMiddleware) getUserFromDatabaseWithToken(token string) (*models.Use
 // getUserFromDatabase looks up the token in the database and caches the
 // resulting user record in memory.
 // Deprecated: Use getUserFromDatabaseWithToken for new code paths that need expiry checking.
-func (m *AuthMiddleware) getUserFromDatabase(token string) (*models.User, error) {
-	user, _, err := m.getUserFromDatabaseWithToken(token)
+func (m *AuthMiddleware) getUserFromDatabase(ctx context.Context, token string) (*models.User, error) {
+	user, _, err := m.getUserFromDatabaseWithToken(ctx, token)
 	return user, err
 }