feat: add optional slog.Logger support for observability

[christiangda]

Summary

• Add WithLogger(*slog.Logger) to Provider for optional structured logging with zero overhead when disabled
• Log component collection results, fallback paths (e.g. system_profiler → ioreg), command execution timing, and errors
• Thread *slog.Logger through all platform collectors (darwin, linux, windows), executor, and network functions
• Update all README and doc.go code examples with context.Context parameter
• Add TestWithLoggerOutput and TestWithoutLoggerNoOutput verification tests

Log Levels

Level	What's Logged
Info	Component collected, fallback triggered, ID generation lifecycle
Warn	Component failed or returned empty value
Debug	Command execution details (name, args, duration), raw hardware values

Test plan

• go build ./... compiles across all platforms
• go test -v -race -count=1 ./... — all tests pass
• go vet ./... — no warnings
• New test verifies log output appears with logger and doesn't appear without
• Manual test with slog.NewTextHandler and slog.NewJSONHandler

🤖 Generated with Claude Code

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