Improve docker-compose local development docs and examples

[AnnabelJoe]

Category: DevOps

Description: Ensure local development instructions are complete, accurate, and include required .env examples.

Acceptance Criteria:

• README/docker docs include exact cp ... .env.local steps
• Required env vars are listed for local compose
• Compose startup instructions mention port and dependency readiness

Priority: Medium
Estimated Effort: Small
Dependencies: documentation updates
Suggested Labels: devops, documentation