Replace all 27 instances of fmt.Errorf/errors.New in production code
with coreerr.E() from forge.lthn.ai/core/go-log for structured error
context (op, message, cause). Promote go-log from indirect to direct
dependency in go.mod.
Co-Authored-By: Virgil <virgil@lethean.io>
Replace all os.ReadFile, os.WriteFile, os.MkdirAll, os.Remove calls in
pidfile.go and registry.go with coreio.Local equivalents (Read, Write,
EnsureDir, Delete). Add forge.lthn.ai/core/go-io v0.1.2 as a direct dependency.
Co-Authored-By: Virgil <virgil@lethean.io>
PIDFile manages a process ID lock file with Acquire/Release semantics.
Detects stale PIDs via signal(0) probe, creates parent directories
automatically. Includes standalone ReadPID helper for checking if a
PID file's process is still alive.
Co-Authored-By: Virgil <virgil@lethean.io>
