task 6: narrow service interfaces in Server and Middleware

Split Server struct to accept narrow service interfaces instead of fat
composites (MediaService, AdminService). Each handler now depends only on
its specific slice (MediaBrowseService, MediaWriteService, etc.).

Split Middleware to depend on a narrow UserStore interface instead of full
repository.Store. Updated all constructors, call sites, and tests.

Added negative tests for nil AdminService and ProgressService returning
501 Not Implemented.

References task 6.

1 files changed, 8 insertions, 3 deletions

diff --git a/internal/api/middleware.go b/internal/api/middleware.go
index bc19fc8..c6cc303 100644
--- a/internal/api/middleware.go
+++ b/internal/api/middleware.go
@@ -7,7 +7,6 @@ import (
 
 	"codeberg.org/snonux/player/internal/auth"
 	"codeberg.org/snonux/player/internal/model"
-	"codeberg.org/snonux/player/internal/repository"
 )
 
 type ctxKey int
@@ -17,14 +16,20 @@ const (
 	userCtxKey
 )
 
+// UserStore is the narrow interface Middleware needs for user lookups.
+type UserStore interface {
+	CountUsers(ctx context.Context) (int, error)
+	GetUserByID(ctx context.Context, id int64) (*model.User, error)
+}
+
 // Middleware holds dependencies for middleware constructors.
 type Middleware struct {
-	store repository.Store
+	store UserStore
 	sm    *auth.SessionManager
 }
 
 // NewMiddleware creates middleware handlers.
-func NewMiddleware(store repository.Store, sm *auth.SessionManager) *Middleware {
+func NewMiddleware(store UserStore, sm *auth.SessionManager) *Middleware {
 	return &Middleware{store: store, sm: sm}
 }