fix: MetalRT segfault crashes, missing dylib packaging, and M5+ forward-compatibility (#19)

* refactor: remove all benchmarking code and metrics except TTFA

Remove the entire benchmark subsystem and inline performance metrics
(tok/s, TTFT, prefill, decode, STT ms, TTS ms) while preserving
TTFA (Time To First Audio) tracking throughout the pipeline.

Deleted:
- src/bench/ directory (benchmark.h, benchmark.cpp)
- rcli bench CLI command and all bench arguments
- rcli metalrt bench subcommand
- [B] bench panel and [V] verbose metrics toggle in TUI
- API functions: rcli_benchmark, rcli_run_full_benchmark,
  rcli_get_last_llm_perf, rcli_get_last_llm_perf_extended,
  rcli_get_last_tts_perf, rcli_get_last_stt_perf
- print_llm_perf, print_tts_perf, print_stt_perf helpers

Preserved:
- TTFA tracking and display in TUI models panel
- rcli_get_context_info (context window gauge)
- Voice bench test (TTFA-only) in test_pipeline.cpp

* fix: MetalRT segfault on M3/M4, missing dylib packaging, null engine fallback

Addresses three distinct crash scenarios from issue #5:

1. MetalRT GPU crash guard now covers verification inference. The crash
   guard (SIGSEGV handler + breadcrumb) previously only protected
   metalrt_.init() but the actual Metal GPU compute can segfault on
   certain M3/M4 hardware. Now a verification generate runs inside the
   protected section — if it crashes, the breadcrumb persists and next
   launch falls back to llama.cpp. Also removed the unprotected warm-up
   call from main.cpp.

2. package.sh now fails if libonnxruntime is missing instead of silently
   producing an incomplete tarball. Added a recursive fallback search
   path and post-copy validation that checks every @rpath dylib the
   binary references is present in lib/.

3. Defensive null checks: when MetalRT verification fails, attempts late
   llama.cpp init as fallback. Added null-safety guard in
   rcli_process_command MetalRT path. Final validation catches
   impossible states (MetalRT flagged active but not initialized).

Closes #5


* fix: future-proof Metal 3.1 chip detection for M5+ support

Switch gpu_supports_metal31() from an allowlist (M3, M4) to a denylist
(M1, M2) so future Apple Silicon generations are automatically supported
without requiring a code change each generation.

---------

Co-authored-by: AmanSwar <aman.swar001@gmail.com>

Author: shubhammalhotra28

CMakeLists.txt

@@ -104,7 +104,6 @@ add_library(rcli STATIC
     src/pipeline/orchestrator.cpp
     src/pipeline/sentence_detector.cpp
     src/tools/tool_engine.cpp
-    src/bench/benchmark.cpp
 
     # --- RAG retrieval engine ---
     src/engines/embedding_engine.cpp

Formula/rcli.rb

@@ -40,8 +40,6 @@ def caveats
         rcli models             # manage all AI models (LLM, STT, TTS)
         rcli cleanup            # remove unused models to free disk space
 
-      Benchmarks:
-        rcli bench              # run all benchmarks (STT, LLM, TTS, E2E)
     EOS
   end
 

scripts/package.sh

@@ -40,7 +40,13 @@ if [ -z "$ONNX_DYLIB" ]; then
     ONNX_DYLIB=$(find "$BUILD_DIR/_deps/onnxruntime-src/lib" -name "libonnxruntime.*.dylib" ! -name "libonnxruntime.dylib" 2>/dev/null | head -1)
 fi
 if [ -z "$ONNX_DYLIB" ]; then
-    echo "  WARNING: Could not find versioned libonnxruntime dylib"
+    ONNX_DYLIB=$(find "$BUILD_DIR" -name "libonnxruntime.*.dylib" ! -name "libonnxruntime.dylib" 2>/dev/null | head -1)
+fi
+if [ -z "$ONNX_DYLIB" ]; then
+    echo "  ERROR: Could not find versioned libonnxruntime dylib anywhere in $BUILD_DIR"
+    echo "  Searched: _deps/onnxruntime-src/lib and recursive fallback"
+    echo "  The packaged binary will fail with dyld errors without this library."
+    exit 1
 fi
 DYLIBS+=("$ONNX_DYLIB")
 
@@ -59,6 +65,35 @@ if [ ! -f "$DIST_DIR/lib/libonnxruntime.dylib" ] && [ -f "$DIST_DIR/lib/$ONNX_BA
     (cd "$DIST_DIR/lib" && ln -sf "$ONNX_BASENAME" libonnxruntime.dylib)
 fi
 
+# --- Validate all required dylibs are present ---
+echo ""
+echo "Validating packaged dylibs..."
+REQUIRED_LIBS=(libllama libggml libsherpa-onnx-c-api libonnxruntime)
+MISSING=0
+for req in "${REQUIRED_LIBS[@]}"; do
+    if ! ls "$DIST_DIR/lib/"${req}* 1>/dev/null 2>&1; then
+        echo "  ERROR: Required library missing: $req"
+        MISSING=1
+    fi
+done
+
+# Verify the binary can find its dylibs via otool
+NEEDED=$(otool -L "$DIST_DIR/bin/rcli" | grep '@rpath' | awk '{print $1}' | sed 's|@rpath/||')
+for lib in $NEEDED; do
+    if [ ! -f "$DIST_DIR/lib/$lib" ] && [ ! -L "$DIST_DIR/lib/$lib" ]; then
+        echo "  ERROR: Binary references @rpath/$lib but it's not in lib/"
+        MISSING=1
+    fi
+done
+
+if [ "$MISSING" -ne 0 ]; then
+    echo ""
+    echo "  Package is incomplete — missing required shared libraries."
+    echo "  The binary will crash with dyld errors on user machines."
+    exit 1
+fi
+echo "  All required dylibs present."
+
 echo ""
 echo "Fixing rpaths..."