Proposed changes

Adds environment-based device filtering across the full stack:

• config_helper.py: Strips environment from receiver output (not accepted by OTel collector), generates environment-specific processor configs, and splits pipelines by environment
• OTel config: Replaces inline processors with ${file:...} reference to generated_processors.yaml
• Grafana dashboards (18 dashboards): Adds environment dropdown variable; scopes device_name dropdown by selected environment; adds environment=~"$environment" filter to all PromQL queries
• Config defaults: environment defaults to production; not required

Describe the use case and detail of the change. If this PR addresses an issue on GitHub, make sure to include a link to that issue using one of the supported keywords in this PR's description or commit message.

Closes #274

Checklist

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