feat: add min_replicas=1 for dev ACA environments

## Context
ACA apps with min_replicas=0 scale to zero between deploys. Cold start can serve stale placeholder revisions, causing flaky health checks and delayed response on first request.

## Recommendation (AzureContainerAppsSpecialist)
- Set min_replicas=1 for dev environments (cost: ~\.03/hr per app x 8 = negligible)
- Remove \ emplate[0].min_replicas\ from \ignore_changes\ in \infra/terraform/main.tf\
- Add a \min_replicas\ variable with per-environment defaults

## Impact
- Eliminates cold-start race condition
- Makes post-deploy health checks reliable
- No production impact (prod should also be min_replicas=1)

## Files
- \infra/terraform/main.tf\ — ACA resource definition (line ~196)