feat(backend): enhance database indexes for AgentGraph and AgentGraphExecution performance (#10985)

## Summary

Enhances database performance by improving indexes on `AgentGraph` and
`AgentGraphExecution` tables for better query efficiency.

### Changes 🏗️

- **Database Schema**: Updated Prisma schema to enhance database indexes
- Modified `AgentGraph` index from `[userId, isActive]` to `[userId,
isActive, id, version]` for better compound query performance
- Enhanced `AgentGraphExecution` index from `[userId]` to `[userId,
isDeleted, createdAt]` to support filtered queries with sorting
- **Migration**: Auto-generated Prisma migration to implement the index
changes
- Drops existing indexes: `AgentGraph_userId_isActive_idx` and
`AgentGraphExecution_userId_idx`
- Creates new compound indexes:
`AgentGraph_userId_isActive_id_version_idx` and
`AgentGraphExecution_userId_isDeleted_createdAt_idx`

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
  - [x] Verified migration runs successfully
  - [x] Confirmed database queries continue to work with new indexes
  - [x] Tested that existing functionality remains unaffected

#### For configuration changes:
- [x] `.env.default` is updated or already compatible with my changes
- [x] `docker-compose.yml` is updated or already compatible with my
changes
- [x] I have included a list of my configuration changes in the PR
description (under **Changes**)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

autogpt_platform/backend/migrations/20250924230049_enhance_graph_and_execution_index/migration.sql

@@ -0,0 +1,11 @@
+-- DropIndex
+DROP INDEX "AgentGraph_userId_isActive_idx";
+
+-- DropIndex
+DROP INDEX "AgentGraphExecution_userId_idx";
+
+-- CreateIndex
+CREATE INDEX "AgentGraph_userId_isActive_id_version_idx" ON "AgentGraph"("userId", "isActive", "id", "version");
+
+-- CreateIndex
+CREATE INDEX "AgentGraphExecution_userId_isDeleted_createdAt_idx" ON "AgentGraphExecution"("userId", "isDeleted", "createdAt");

autogpt_platform/backend/schema.prisma

@@ -135,7 +135,7 @@ model AgentGraph {
   StoreListingVersions StoreListingVersion[]
 
   @@id(name: "graphVersionId", [id, version])
-  @@index([userId, isActive])
+  @@index([userId, isActive, id, version])
   @@index([forkedFromId, forkedFromVersion])
 }
 
@@ -377,7 +377,7 @@ model AgentGraphExecution {
   sharedAt    DateTime?
 
   @@index([agentGraphId, agentGraphVersion])
-  @@index([userId])
+  @@index([userId, isDeleted, createdAt])
   @@index([createdAt])
   @@index([agentPresetId])
   @@index([shareToken])