- Add integration-tests job in GitHub Actions (runs on PRs only)
- Add explicit resource requests/limits to all workflow templates
  - convert-geozarr: 6Gi/10Gi memory, 2/4 CPU
  - validate: 2Gi/4Gi memory, 1/2 CPU
  - register-stac: 1Gi/2Gi memory, 500m/1 CPU
  - augment-stac: 1Gi/2Gi memory, 500m/1 CPU

Prevents pod eviction and enables predictable scheduling

Add OVERRIDE_GROUPS, OVERRIDE_EXTRA_FLAGS, OVERRIDE_SPATIAL_CHUNK,
OVERRIDE_TILE_WIDTH environment variables to override collection registry
defaults at runtime.

Enables production parameter tuning and testing without code deployment.

Tests: 97 passing (+7), coverage: 91% for get_conversion_params.py

Replace logger.error() calls with logger.exception() to capture full stack
traces in production Kubernetes logs. Adds structured context via extra={}
for improved observability:
- load_payload: Include file path on FileNotFoundError/JSONDecodeError
- format_routing_key: Show template and available fields on KeyError
- main: Include exchange/routing_key/host on publish failure

Closes phase3-analysis #1 (error logging completion)

- Add scripts/metrics.py with 7 Prometheus metrics definitions
- Add CLI timing logs to register_stac.py
- Expose metrics endpoint in workflow pods (port 8000)
- Add prometheus-client dependency
- Background metrics server with trap cleanup

Instrument register_stac.py and augment_stac_item.py with Prometheus
metrics for production observability.

Metrics:
- stac_registration_total: track create/update/skip/replace operations
- stac_http_request_duration_seconds: STAC API latency
- preview_generation_duration_seconds: augmentation timing
- preview_http_request_duration_seconds: preview API latency

SLOs: success >99%, STAC API <500ms, preview <10s

Docs: docs/prometheus-metrics.md with queries, alerts, dashboards

Add metrics calls to register_stac.py and augment_stac_item.py:
- Wrap HTTP operations with duration timers
- Increment operation counters (create/update/skip/replace)
- Track preview generation duration
- All 42 unit tests pass, coverage: augment 24%, register 42%, metrics 65%

- Fix Dockerfile: install from pyproject.toml (ensures dep sync)
- Update workflow template to use feat-prometheus-metrics image
- Add metrics port 8000 to register-stac container

Verified: docker smoke tests, metrics endpoint (7 metrics), k8s template applied