feat(gateway): WorkspaceService + ProjectBootstrapService + TeamsService (P8-015)

- WorkspaceService: path resolution, git init/clone, directory lifecycle (create/delete/exists), user and team root provisioning
- ProjectBootstrapService: orchestrates DB record creation (via Brain) + workspace directory init in a single call
- TeamsService: isMember, canAccessProject, findAll, findById, listMembers via Drizzle DB queries
- WorkspaceController: POST /api/workspaces — auth-guarded project bootstrap endpoint
- TeamsController: GET /api/teams, /:teamId, /:teamId/members, /:teamId/members/:userId
- WorkspaceModule wired into AppModule
- workspace.service.spec.ts: 5 unit tests for resolvePath (user, team, fallback, env var, default)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/gateway/src/workspace/workspace.service.ts

@@ -0,0 +1,111 @@
+import { Injectable, Logger } from '@nestjs/common';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { execFile } from 'node:child_process';
+import { promisify } from 'node:util';
+
+const execFileAsync = promisify(execFile);
+
+export interface WorkspaceProject {
+  id: string;
+  ownerType: 'user' | 'team';
+  userId: string;
+  teamId: string | null;
+}
+
+@Injectable()
+export class WorkspaceService {
+  private readonly logger = new Logger(WorkspaceService.name);
+  private readonly mosaicRoot: string;
+
+  constructor() {
+    this.mosaicRoot = process.env['MOSAIC_ROOT'] ?? '/opt/mosaic';
+  }
+
+  /**
+   * Resolve the workspace path for a project.
+   * Solo: $MOSAIC_ROOT/.workspaces/users/<userId>/<projectId>/
+   * Team: $MOSAIC_ROOT/.workspaces/teams/<teamId>/<projectId>/
+   */
+  resolvePath(project: WorkspaceProject): string {
+    if (project.ownerType === 'team' && project.teamId) {
+      return path.join(this.mosaicRoot, '.workspaces', 'teams', project.teamId, project.id);
+    }
+    return path.join(this.mosaicRoot, '.workspaces', 'users', project.userId, project.id);
+  }
+
+  /**
+   * Create a workspace directory and initialize it as a git repo.
+   * If repoUrl is provided, clone instead of init.
+   */
+  async create(project: WorkspaceProject, repoUrl?: string): Promise<string> {
+    const workspacePath = this.resolvePath(project);
+
+    // Create directory
+    await fs.mkdir(workspacePath, { recursive: true });
+
+    if (repoUrl) {
+      // Clone existing repo
+      await execFileAsync('git', ['clone', repoUrl, '.'], { cwd: workspacePath });
+      this.logger.log(`Cloned ${repoUrl} into workspace ${workspacePath}`);
+    } else {
+      // Init new git repo
+      await execFileAsync('git', ['init'], { cwd: workspacePath });
+      await execFileAsync('git', ['commit', '--allow-empty', '-m', 'Initial workspace commit'], {
+        cwd: workspacePath,
+        env: {
+          ...process.env,
+          GIT_AUTHOR_NAME: 'Mosaic',
+          GIT_AUTHOR_EMAIL: 'mosaic@localhost',
+          GIT_COMMITTER_NAME: 'Mosaic',
+          GIT_COMMITTER_EMAIL: 'mosaic@localhost',
+        },
+      });
+      this.logger.log(`Initialized git workspace at ${workspacePath}`);
+    }
+
+    return workspacePath;
+  }
+
+  /**
+   * Delete a workspace directory recursively.
+   */
+  async delete(project: WorkspaceProject): Promise<void> {
+    const workspacePath = this.resolvePath(project);
+    try {
+      await fs.rm(workspacePath, { recursive: true, force: true });
+      this.logger.log(`Deleted workspace at ${workspacePath}`);
+    } catch (err) {
+      this.logger.warn(`Failed to delete workspace at ${workspacePath}: ${err}`);
+    }
+  }
+
+  /**
+   * Check whether the workspace directory exists.
+   */
+  async exists(project: WorkspaceProject): Promise<boolean> {
+    const workspacePath = this.resolvePath(project);
+    try {
+      await fs.access(workspacePath);
+      return true;
+    } catch {
+      return false;
+    }
+  }
+
+  /**
+   * Create the base user workspace directory (call on user registration).
+   */
+  async createUserRoot(userId: string): Promise<void> {
+    const userRoot = path.join(this.mosaicRoot, '.workspaces', 'users', userId);
+    await fs.mkdir(userRoot, { recursive: true });
+  }
+
+  /**
+   * Create the base team workspace directory (call on team creation).
+   */
+  async createTeamRoot(teamId: string): Promise<void> {
+    const teamRoot = path.join(this.mosaicRoot, '.workspaces', 'teams', teamId);
+    await fs.mkdir(teamRoot, { recursive: true });
+  }
+}