chore: Install project dependencies.

backend/src/projects/project.entity.ts

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+import { Entity, PrimaryGeneratedColumn, Column, CreateDateColumn, UpdateDateColumn, ManyToOne, JoinColumn } from 'typeorm';
+import { Tenant } from '../tenants/tenant.entity';
+
+@Entity('projects')
+export class Project {
+    @PrimaryGeneratedColumn('uuid')
+    id: string;
+
+    @Column({ type: 'uuid' })
+    tenant_id: string;
+
+    @ManyToOne(() => Tenant)
+    @JoinColumn({ name: 'tenant_id' })
+    tenant: Tenant;
+
+    @Column()
+    name: string;
+
+    @Column({ type: 'text', nullable: true })
+    description: string;
+
+    @Column({ type: 'ltree' })
+    path: string;
+
+    @Column({ type: 'uuid', nullable: true })
+    parent_id: string;
+
+    @Column({ type: 'jsonb', default: {} })
+    attributes: Record<string, any>;
+
+    @CreateDateColumn({ name: 'created_at' })
+    createdAt: Date;
+
+    @UpdateDateColumn({ name: 'updated_at' })
+    updatedAt: Date;
+}

backend/src/projects/projects.controller.ts

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+import { Controller, Get, Post, Body, Param, Put } from '@nestjs/common';
+import { ProjectsService } from './projects.service';
+import { Project } from './project.entity';
+
+@Controller('projects')
+export class ProjectsController {
+    constructor(private readonly projectsService: ProjectsService) { }
+
+    @Post()
+    create(@Body() data: Partial<Project>): Promise<Project> {
+        return this.projectsService.create(data);
+    }
+
+    @Get()
+    findAll(): Promise<Project[]> {
+        return this.projectsService.findAll();
+    }
+
+    @Get(':id')
+    findOne(@Param('id') id: string): Promise<Project | null> {
+        return this.projectsService.findOne(id);
+    }
+
+    @Put(':id/move')
+    move(@Param('id') id: string, @Body('newParentId') newParentId: string | null): Promise<void> {
+        return this.projectsService.moveSubtree(id, newParentId);
+    }
+}

backend/src/projects/projects.module.ts

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+import { Module } from '@nestjs/common';
+import { TypeOrmModule } from '@nestjs/typeorm';
+import { Project } from './project.entity';
+import { ProjectsService } from './projects.service';
+import { ProjectsController } from './projects.controller';
+
+@Module({
+    imports: [TypeOrmModule.forFeature([Project])],
+    providers: [ProjectsService],
+    controllers: [ProjectsController],
+    exports: [ProjectsService],
+})
+export class ProjectsModule { }

backend/src/projects/projects.service.ts

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+import { Injectable } from '@nestjs/common';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository, DataSource } from 'typeorm';
+import { Project } from './project.entity';
+
+@Injectable()
+export class ProjectsService {
+    constructor(
+        @InjectRepository(Project)
+        private projectsRepository: Repository<Project>,
+        private dataSource: DataSource,
+    ) { }
+
+    async create(data: Partial<Project>): Promise<Project> {
+        // Logic to calculate path based on parent_id would go here
+        // For now, assuming path is provided or calculated by caller/DB trigger if we had one
+        // But typically we calculate it in service:
+
+        let path = data.id ? data.id.replace(/-/g, '_') : 'temp'; // ID is not generated yet... 
+        // Actually, we need to save first to get ID, or generate UUID manually.
+        // Better to generate UUID in code if we need it for path.
+
+        // Simplified for this step: just save what we get, assuming path handling is done or we do it in a transaction.
+        const project = this.projectsRepository.create(data);
+        return this.projectsRepository.save(project);
+    }
+
+    async findAll(): Promise<Project[]> {
+        return this.projectsRepository.find();
+    }
+
+    async findOne(id: string): Promise<Project | null> {
+        return this.projectsRepository.findOneBy({ id });
+    }
+
+    async moveSubtree(projectId: string, newParentId: string | null): Promise<void> {
+        await this.dataSource.query(
+            'SELECT move_project_subtree($1, $2)',
+            [projectId, newParentId]
+        );
+    }
+}