ci(build): do not run the release matrix for internal v0.0.0-* tags

`v0.0.0-*` is this repository's existing marker for a tag that is not a
product version — a place to hang a binary needing a permanent public
URL, the way `v0.0.0-stt-models` hosts the 360 MB Whisper model.

`build.yml` triggers on `v*` with no further filter, so creating one runs
the entire matrix — Windows, macOS x2, Linux, installers, notarisation —
to publish an archive it was never asked to build. That has already
happened once: there is a `build.yml` run against a `v0.0.0` tag in the
history.

The reason this matters now is #591: adopting a locally built ONNX
Runtime means publishing it under such a tag, and doing that should not
cost a full release build every time the pinned version moves.

The other five release-triggered workflows do NOT need the same guard,
which was checked rather than assumed: `aur-publish`, `bump-nix-package`,
`publish-winget` and `update-homebrew-cask` all gate on
`!github.event.release.prerelease`, and an internal release is marked as
a prerelease — so none of them can push a bogus version to a package
manager. `announce-release` has no such gate and would post to Discord;
that is noise rather than a wrong publication, and whether an internal
release deserves an announcement is a call for whoever owns the channel,
so it is left alone here.

Author: EtienneLescot

.github/workflows/build.yml

@@ -4,6 +4,19 @@ on:
   push:
     tags:
       - "v*"
+      # `v0.0.0-*` is this repository's marker for a tag that is NOT a product
+      # version — a place to hang a binary that needs a permanent public URL, the
+      # way `v0.0.0-stt-models` hosts the 360 MB Whisper model. Without this
+      # exclusion, creating one runs the whole matrix — Windows, macOS x2, Linux,
+      # installers, notarisation — to publish an archive nobody asked it to build.
+      # That has already happened once.
+      #
+      # The other five release-triggered workflows do not need the same guard:
+      # AUR, Nix, winget and Homebrew all gate on
+      # `!github.event.release.prerelease`, and an internal release is marked as a
+      # prerelease. Only the Discord announcement still fires, which is noise
+      # rather than a wrong publication.
+      - "!v0.0.0-*"
   workflow_dispatch:
     inputs:
       arch: