HAVC installer v2.9.1

HAVC installer v2.9.1 — a faster video probe, VFR-safe muxing, and an explicit temp-folder cleanup.
The GUI now reads a source video's details with ffprobe instead of a VapourSynth
probe: 0.02–0.05 s even on a two-hour 1080p feature (it was ~1.1 s), and the panel
gained a Duration field in hh:mm:ss. The MKV mux no longer decodes the whole
film to read its timestamps — that cost 121 s at the end of every encode on a 2.3 GB
feature — and it now detects "soft" variable-frame-rate sources that no header test
can see, so their duration is preserved. ffprobe ships with its license text in
tools.zip, and Select Reference Frames only deletes ref_tht10_temp when the new
Del tht10_temp checkbox asks for it. Updates are incremental: no environment rebuild.

Start here:

• HAVC-Setup-2.9.1.exe — HAVC Manager installer wizard (single-file, self-contained: no .NET
  runtime needed). Windows SmartScreen may warn (Windows protected your PC → More info →
  Run anyway); the exe is not code-signed yet. sha256: bed91756e5669d46b089e25100b577134a05e9ff74e5f90930639246acc8109b
• havc-2.9.1-py3-none-any.whl — HAVC server stack wheel: the content the manager installs (its
  version follows the installer). sha256: c6020645c45708238224d224004db1a6be1f4dc83bb07b95e8d9e6420b0be133
• release.json — the release manifest read by the installer/manager (sha256 for every artifact).
  Pinned packages and the ComfyUI runtime live in the stable asset release HAVC Assets v1.0.8;
  vscmnet2 comes from dan64/vs-cmnet2.

Requirements: Windows 10/11, NVIDIA RTX 30/40/50, CUDA 13.0+. Model weights are downloaded on
first use and preserved across updates. ffprobe is required for the video details, for the
timestamp-preserving mux and (since this release) for the frame count: the installer ships it as
tools\ffmpeg\ffprobe.exe, a GPL-3.0 build with its license text — see docs/third-party.md.
Without it the GUI logs a warning and muxes at a constant frame rate.

Notes: installer releases (and their wheel) stay on the 2.x.x line; the 1.x.x tags are reserved
for asset buckets. The update is incremental (requires_env_rebuild: false) and re-extracts
tools.zip once, because the archive now carries ffprobe.exe and its license. The manager does
not update its own exe while it is running: after updating from 2.9.0, manager_version keeps the
old value until you run HAVC-Setup-2.9.1.exe (Update/Repair copies the running exe). The
Del tht10_temp checkbox is off by default: with Move Files off, ref_tht10_temp is the
backup of every candidate frame, and Dry Run or Stop never delete it.

Docs: docs/ in the repository.