added: profiling toolchain (py-spy, pyinstrument, pytest-benchmark, memray, snakeviz)

New `profile` optional-deps group, opt-in Pyinstrument ASGI middleware
gated by DECNET_PROFILE_REQUESTS, bench marker + tests/perf/ micro-benchmarks
for repository hot paths, and scripts/profile/ helpers for py-spy/cProfile/memray.

scripts/profile/pyspy-attach.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+# Attach py-spy to the running DECNET uvicorn worker(s) and record a flamegraph.
+# Requires sudo on Linux because of kernel.yama.ptrace_scope=1 by default.
+set -euo pipefail
+
+DURATION="${DURATION:-30}"
+OUT="${OUT:-profiles/pyspy-$(date +%s).svg}"
+mkdir -p "$(dirname "$OUT")"
+
+PID="$(pgrep -f 'uvicorn decnet.web.api' | head -n 1 || true)"
+if [[ -z "${PID}" ]]; then
+    echo "No uvicorn worker found. Start the API first (e.g. 'decnet deploy ...')." >&2
+    exit 1
+fi
+
+echo "Attaching py-spy to PID ${PID} for ${DURATION}s -> ${OUT}"
+sudo py-spy record -o "${OUT}" -p "${PID}" -d "${DURATION}" --subprocesses
+echo "Wrote ${OUT}"