Add pm2 ecosystem config with production TASKS_DIRECTORY#

Problem#

The viewer backend reads TASKS_DIRECTORY from the environment, defaulting to ./tasks. After agent-core centralised artefact storage to /home/agent/AgentSDE/tasks/production, the VPS deployment had no way to pick up the new path automatically.

Task / Link#

Closes #10

Changes#

• Add ecosystem.config.js at repo root: pm2 app named viewerv2-backend, dist/main.js entry, TASKS_DIRECTORY=/home/agent/AgentSDE/tasks/production in env_production
• Update .env.example: add comment documenting the production TASKS_DIRECTORY value

Notes#

• pm2 on VPS must be restarted with pm2 start ecosystem.config.js --env production after deploy for the new config to take effect — operational step outside PR scope.

Testing#

• Config-only change (no TS code); lint and tests have no relevant coverage to run.