Support independent OTLP logs and metrics channels in Helm validation and egress

Description

Audit dimension 4 confirmed a high live deployment defect at the v2.0.0 release tree. core/config_models.py:534-615 and 718-738 make tracing, data logs and bridged metrics independent channels with endpoint inheritance. Helm emits all three channel settings in charts/meraki-dashboard-exporter/templates/configmap.yaml:156-205, but templates/_validation.tpl:34-44 validates only tracing, and templates/networkpolicy.yaml:49-58 opens the configured OTLP egress port only when tracing is enabled. A logs-only or metrics-only chart can render without any endpoint and then fail application startup; with NetworkPolicy enabled, a valid logs-only or metrics-only deployment can omit the collector port and block export. Focused helm renders reproduced both states, while existing chart tests cover generated mapping and shutdown validation only.

Acceptance Criteria

• #1 Helm rendering rejects each enabled tracing, logs or metrics channel when neither its own endpoint nor the shared endpoint resolves
• #2 The configured OTLP NetworkPolicy egress port is emitted when any tracing, logs or metrics channel is enabled
• #3 Focused renders cover tracing-only, logs-only, metrics-only, inherited endpoints and independent endpoints without changing application endpoint semantics

Definition of Done

• #1 just check (ruff format –check, ruff check, mypy, generated-doc drift, offline API conformance, and the marker-filtered pytest run with the 80% coverage floor — this is exactly what the CI test job runs)
• #2 just gen, when metrics, config, endpoints, collectors, the settings schema or the chart config changed — just check includes the drift gate and CI fails the build on it
• #3 Grafana queries in grafana/dashboards/*.json and grafana/alerts/ updated, if a metric or label name changed

Implementation Plan

1. Add failing Helm-render regressions for logs-only and metrics-only missing endpoints and missing NetworkPolicy OTLP egress. 2. Mirror application endpoint inheritance for all three channels in Helm validation. 3. Treat networkPolicy.egress.otlpPort as the chart-wide OTLP port and emit it when any channel is enabled; distinct channel ports remain available through the existing extraEgress escape hatch. 4. Run focused chart tests and return the uncommitted diff to root.

Implementation Notes

Validation-first evidence: before the templates changed, focused Helm renders had 4 failures out of 10 because logs-only and metrics-only missing endpoints rendered and their NetworkPolicies omitted port 4317. After the fix, all 10 focused renders passed and helm lint reported 1 chart linted, 0 failed. Integrated just check passed 2,939 tests with 5 deselected at 91.25% coverage, and just ci passed all Docker legs. Distinct channel ports remain available through existing extraEgress; no application endpoint, metric or label semantics changed.

Final Summary

Implemented in 31c1d25: Helm now mirrors application endpoint inheritance for each independent OTLP signal and opens the declared OTLP egress port whenever any signal is enabled. Verified through tracing-only, logs-only, metrics-only, inherited and independent endpoint renders.