fix: set authenticated user on request context in bearer token auth

tryBearerAuth validated the bearer token but never looked up the
associated user or set it on the request context. This meant
downstream handlers calling GetCurrentUser would get nil even
with a valid token.

Changes:
- Add ContextWithUser/UserFromContext helpers in auth package
- tryBearerAuth now looks up the user by token's UserID and
  sets it on the request context via auth.ContextWithUser
- GetCurrentUser checks context first before falling back to
  session cookie
- Add integration tests for bearer auth user context

internal/middleware/middleware.go

@@ -386,8 +386,8 @@ func (m *Middleware) APISessionAuth() func(http.Handler) http.Handler {
 			request *http.Request,
 		) {
 			// Try Bearer token first.
-			if m.tryBearerAuth(request) {
-				next.ServeHTTP(writer, request)
+			if authedReq, ok := m.tryBearerAuth(request); ok {
+				next.ServeHTTP(writer, authedReq)
 
 				return
 			}
@@ -457,16 +457,19 @@ func (m *Middleware) SetupRequired() func(http.Handler) http.Handler {
 }
 
 // tryBearerAuth checks for a valid Bearer token in the
-// Authorization header.
-func (m *Middleware) tryBearerAuth(request *http.Request) bool {
+// Authorization header. On success it returns a new request
+// with the authenticated user set on the context.
+func (m *Middleware) tryBearerAuth(
+	request *http.Request,
+) (*http.Request, bool) {
 	authHeader := request.Header.Get("Authorization")
 	if !strings.HasPrefix(authHeader, bearerPrefix) {
-		return false
+		return request, false
 	}
 
 	rawToken := strings.TrimPrefix(authHeader, bearerPrefix)
 	if rawToken == "" {
-		return false
+		return request, false
 	}
 
 	tokenHash := database.HashAPIToken(rawToken)
@@ -475,15 +478,26 @@ func (m *Middleware) tryBearerAuth(request *http.Request) bool {
 		request.Context(), m.params.Database, tokenHash,
 	)
 	if err != nil || apiToken == nil {
-		return false
+		return request, false
 	}
 
 	if apiToken.IsExpired() {
-		return false
+		return request, false
+	}
+
+	// Look up the user associated with the token.
+	user, err := models.FindUser(
+		request.Context(), m.params.Database, apiToken.UserID,
+	)
+	if err != nil || user == nil {
+		return request, false
 	}
 
 	// Update last_used_at (best effort).
 	_ = apiToken.TouchLastUsed(request.Context())
 
-	return true
+	// Set the authenticated user on the request context.
+	ctx := auth.ContextWithUser(request.Context(), user)
+
+	return request.WithContext(ctx), true
 }