v0.13.0

• Header Restructuring: Headers have been reorganized into counter/, sample/, metric/, analyzer/, and util/ subdirectories and renamed from .h to .hpp. The previous .h headers remain as forwarding includes with deprecation notices and will be removed in v1.0.
• Breaking: EventCounter::add() and start() (including Sampler::start() and all multi-thread/core variants) now return void instead of bool. Errors are communicated via exceptions; the return values were unused.
• Compile Flag for AUX Buffer Support: Added PERFCPP_NO_SAMPLE_AUX compile flag to disable auxiliary buffer sampling on systems with Linux kernels older than 5.5 that lack PERF_SAMPLE_AUX support. Thanks to @rconnorlawson.
• Perf File Export: Fixed bugs in perf format when materializing samples into file that can be read via perf [mem] report.
• NMI Watchdog Detection: Hardware counter detection now accounts for the NMI watchdog permanently consuming one hw-PMU counter, fixing incorrect counter counts on systems with the watchdog enabled.
• RAPL Power Metrics: Added built-in watts-pkg, watts-cores, and watts-ram metrics for measuring power consumption via RAPL energy counters (see the documentation).
• Conan Package: Added Conan 2.x package recipe for easier integration.
• Config Setter Naming: Standardized Config setter naming — setters no longer use the is_ prefix (e.g., pinned(bool) instead of is_pinned(bool)). The old is_pinned(bool) and is_debug(bool) setters are deprecated and will be removed in v1.0.
• SampleResult CSV Export: Added SampleResult::to_csv() returning a std::string, complementing the existing file-based overload.
• Per-Element Results: Added result_of_thread(thread_id), result_of_process(process_id), and result_of_core(core_id) to query individual results from MultiThreadEventCounter, MultiProcessEventCounter, and MultiCoreEventCounter. Process and core variants return std::optional<CounterResult> since the ID may not be present.
• Documentation: Rewrote and restructured all documentation pages for consistency, conciseness, and correctness. Documentation is now hosted at jmuehlig.github.io/perf-cpp.