v6.1.8 services stack: wave-4 daemon/IPC + packaging hardening

Wave-4 audit loop: 25 issues filed (#2418-#2442), all fixed in 21301f8 + allowlist drift fix, verified, closed.

Daemon/IPC (#2418-#2431): flag-only signal handlers, APIServer.stop join with started-event, signal setup on start(), SIGHUP reload flag, port-keyed lockfile without truncate, bind-success fail-fast, WS-only query token, per-connection rate key, to_thread events dispatch, TTS speed validation + serialized synthesis, unified worker pause + queue lock, supervisor N-failure tolerance, verified-pid port SIGTERM, Event-based supervisor shutdown.

Packaging/installer (#2432-#2442): cu129 installer index + pinned torch stack, torch-needs extended, constraints header rewritten, README pins, Dockerfile release defaults, docker-compose.release.yml, computer_use marked/dropped, run_tests prefix map, native floors raised, debian comment fixed.

Note: setup.py/constraints also carry the parallel dep lane's in-flight pillow 13.0.0/certifi regen; verification here ran on installed pillow 12.2.0 — pillow-13 runtime risk stays with that lane.

Gate: 1516 passed (1494 full-suite + 22 RAG/idle), 24 skipped, 0 segfaults. Remaining red, all classified: functional qwen e2e needs CUDA llama build (#2416, env), ollama pull_stream 501 in parity lane (#2415), P05 scipy collect-parent missing from venv (pre-existing env gap). Excluded: test_fp8_scaled_mm.py order-dependent segfault (#2276). Still open: #2274 dep majors, #2276, #2358/#2363-#2365 owner-decision, #2399 docs, #2413 vendor publish, #2415, #2416.