Prometheus telemetry

[creativeprojects]

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[Copilot]

Pull request overview

This PR introduces Prometheus/OpenTelemetry-based telemetry to expose runtime metrics (disk temperature/activity and fan zone speed) and adds a built-in HTTP endpoint for scraping, while also updating the simulation RNG to math/rand/v2 with two seeds.

Changes:

• Add OpenTelemetry metric instrumentation for disks and fan zones, with a Prometheus exporter.
• Add an HTTP metrics server and wire telemetry/metrics startup + shutdown into main.
• Switch simulation RNG seeding to two uint64 seeds and migrate to math/rand/v2.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
telemetry.go	Creates the OTel Prometheus exporter and initializes telemetry.
metrics.go	Adds the /metrics HTTP server endpoint.
main.go	Wires telemetry + metrics server lifecycle into startup/shutdown.
lib/telemetry.go	Defines OTel metrics (observable gauges) for disks and fan zones.
lib/zone.go	Adds CurrentSpeed() accessor used by telemetry.
lib/control.go	Minor logging message change.
lib/global.go	Switches simulation RNG to math/rand/v2 PCG with two seeds.
lib/simulation/sensor.go	Migrates simulated sensors to math/rand/v2.
lib/simulation/sensor_test.go	Updates tests for math/rand/v2 seeding.
flags.go	Replaces single simulation seed flag with two seed flags.
cfg/config.go	Adds telemetry config and replaces seed config with two seeds.
config.yaml	Adds telemetry configuration example.
go.mod	Adds Prometheus + OpenTelemetry metric dependencies.
go.sum	Updates module checksums for new dependencies.

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