fix(ci): build-ns7zip workflow_dispatch only (decouple from CI-system tags)

build-ns7zip builds an EXTERNAL repo (nsis-plugin-ns7zip). The
`push: tags v*` trigger (inherited from when this workflow lived in
the plugin repo) made every CI-system tag — including the Phase A
marker v2.0.0-phaseA — auto-build and publish an ns7zip release on
the CI-system repo. Remove the tag trigger; manual dispatch only.
The release job's tag-gate `if` now never fires (skipped) — release
flow already validated with a throwaway tag.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/build-ns7zip.yml

@@ -4,14 +4,16 @@
 # and linux-build (SSH) runners using the reusable composite action.
 # Uses: https://gitea.emulab.it/Simone/local-ci-cd-system/.gitea/actions/local-ci-build@main
 #
-# Trigger: push su tag v*, oppure run manuale
+# Trigger: SOLO run manuale (workflow_dispatch).
+# Builda un repo ESTERNO (nsis-plugin-ns7zip): i tag del repo
+# CI-system non c'entrano con le release ns7zip. Il vecchio trigger
+# `push: tags v*` (ereditato da quando il workflow viveva nel repo
+# plugin) faceva auto-buildare+pubblicare ns7zip su ogni tag del
+# CI-system (es. il marker Fase A v2.0.0-phaseA) — rimosso.
 
 name: Build ns7zip (Local CI)
 
 on:
-  push:
-    tags:
-      - 'v*'
   workflow_dispatch:
 
 jobs: