fix: normalize project session payloads

The sidebar had to understand cursorSessions, codexSessions,
and other provider buckets because /api/projects exposed
provider-shaped arrays.

That leaked backend adapter storage into project state and made
frontend behavior drift each time a provider needed another bucket
or exception.

Return one sessions list with provider metadata instead. Project
state, search, and running-session filtering now share one contract,
while provider-specific storage remains behind the backend boundary.

server/modules/projects/services/project-management.service.ts

@@ -30,10 +30,6 @@ type ProjectApiView = {
   isArchived: boolean;
   isStarred: boolean;
   sessions: [];
-  cursorSessions: [];
-  codexSessions: [];
-  geminiSessions: [];
-  opencodeSessions: [];
   sessionMeta: {
     hasMore: false;
     total: 0;
@@ -82,10 +78,6 @@ function mapProjectRowToApiView(projectRow: ProjectRepositoryRow): ProjectApiVie
     isArchived: Boolean(projectRow.isArchived),
     isStarred: Boolean(projectRow.isStarred),
     sessions: [],
-    cursorSessions: [],
-    codexSessions: [],
-    geminiSessions: [],
-    opencodeSessions: [],
     sessionMeta: {
       hasMore: false,
       total: 0,