ci: introduce unified CI Quality Gate with intelligent path filtering

[umesh0492]

Summary

Affected Components

• Docker Compose Local Sandbox (deploy/docker-compose/)
• Kubernetes Manifests / Helm Charts (deploy/kubernetes/)
• ArgoCD GitOps Definitions (deploy/kubernetes/argocd/)
• Terraform Infrastructure as Code (deploy/terraform/)
• Prometheus Alert Rules & SLO Definitions (deploy/*/alerts/, deploy/slo/)
• Grafana Dashboards (deploy/*/grafana/dashboards/)
• OpenTelemetry Collector Pipeline (deploy/*/otel-collector/)
• Incident Runbooks & Architecture Docs (docs/, README.md)

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Strict Quality & Truth-Gate Checklist

Before requesting maintainer review, please verify that all automated verification gates pass locally:

• Version Synchronization: ./scripts/check_version.sh passes with exit code 0 (validating version tags, ArgoCD sync, and truthfulness gates).
• Promtool Alert Unit Tests: bash ./scripts/test_alerts.sh passes with exit code 0 (all test fixtures succeed).
• Alertmanager Config Lint: amtool check-config deploy/kubernetes/alerts/alertmanager.yaml passes without syntax or route errors.
• Terraform Formatting & Validation: terraform -chdir=deploy/terraform fmt -check -recursive and terraform -chdir=deploy/terraform validate succeed.
• Terraform Linting: tflint --recursive passes inside deploy/terraform with zero rule violations.
• Canonical Availability SLI AST Equivalence: Any new or updated availability error-rate expression matches deploy/slo/canonical_sli.promql and strictly excludes 4xx client status codes (status=~"5..").
• Runbook Coverage: All new or modified alerts have a dedicated triage and mitigation SOP documented in docs/RUNBOOKS.md.
• Zero Hardcoded Credentials: No secrets, tokens, or plaintext credentials exist in manifests or configuration files.

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Verification Evidence

# Paste output of:
# ./scripts/check_version.sh
# bash ./scripts/test_alerts.sh
# terraform -chdir=deploy/terraform fmt -check -recursive
# cd deploy/terraform && tflint --recursive

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Related Issues

Fixes #