feat: Plumb in otel metrics

[nssherpa]

Testing

go build -o cachewd ./cmd/cachewd
OTEL_METRICS_ENABLED=true OTEL_METRICS_PORT=9102 ./cachewd
INF Constructing disk cache limit-mb=250000 evict-interval=1m0s root=./state/cache max-ttl=8h0m0s
INF Constructing tiered cache tiers=1
INF Git strategy initialized mirror_root=./state/git-mirrors fetch_interval=15m0s ref_check_interval=10s bundle_interval=24h0m0s
WRN No token configured for github-releases strategy
INF Initialized Go module proxy strategy proxy=https://proxy.golang.org
INF OpenTelemetry metrics initialized with Prometheus exporter service=cachewd
INF Starting cachewd bind=127.0.0.1:8080
INF Starting metrics server port=9102

Metrics exposed

Test Summary
Local Testing
Build and Run:


go build -o dist/cachewd ./cmd/cachewd
./dist/cachewd --config cachew-local.hcl
Health Checks:

Main server (port 8080): ✓ OK
Metrics server (port 9102): ✓ OK
Metrics Endpoint Verification:


curl -s http://localhost:9102/metrics | grep -v '^#' | cut -d'{' -f1 | cut -d' ' -f1 | sort -u
Output:


http_server_duration_milliseconds_bucket
http_server_duration_milliseconds_count
http_server_duration_milliseconds_sum
http_server_request_size_bytes_total
http_server_response_size_bytes_total
otel_scope_info
target_info
Docker Testing
Build and Run:


./bin/just docker::build
docker run -d --name cachew-test -p 8081:8080 -p 9103:9102 \
  -v $(pwd)/cachew-local.hcl:/app/cachew.hcl:ro \
  cachew:local --config /app/cachew.hcl
Health Checks:

Main server (port 8081): ✓ OK
Metrics server (port 9103): ✓ OK
Metrics Endpoint Verification:


curl -s http://localhost:9103/metrics | grep -v '^#' | cut -d'{' -f1 | cut -d' ' -f1 | sort -u
Output:


http_server_duration_milliseconds_bucket
http_server_duration_milliseconds_count
http_server_duration_milliseconds_sum
http_server_request_size_bytes_total
http_server_response_size_bytes_total
otel_scope_info
target_info

[nssherpa]

Trying to see what the License Compliance issue is.