ci: rename build-nsInnoUnp.yml -> build-ns7zip.yml; update doc refs

Workflow now targets Simone/nsis-plugin-ns7zip. Renamed the file and
the workflow `name:`, and updated all references in active docs
(plans/archived and docs/archived left as frozen history).

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

plans/idea-2-linux-host.md

@@ -132,7 +132,7 @@ Finestra di manutenzione concordata:
 3. Verificare nessun job in coda lato Gitea
 4. Avviare act_runner Linux (`systemctl start act-runner`)
 5. Trigger manuale di un workflow di smoke test
-6. Trigger del workflow matrix `build-nsInnoUnp.yml` (Win + Linux build)
+6. Trigger del workflow matrix `build-ns7zip.yml` (Win + Linux build)
 
 Se PASS → cutover confermato. Se FAIL → rollback (riavvio runner Windows,
 nessun dato è stato distrutto).
@@ -205,7 +205,7 @@ Costo: codebase divisa in due ambienti, maggiore overhead operativo.
 - [ ] act_runner gira come systemd service `act-runner.service` su Linux Mint
 - [ ] Tutti i template VM (`WinBuild2025`, `WinBuild2022`, `LinuxBuild2404`)
       operativi dal nuovo host con snapshot integri
-- [ ] Workflow `build-nsInnoUnp.yml` (matrix Win+Linux) PASS dal nuovo host
+- [ ] Workflow `build-ns7zip.yml` (matrix Win+Linux) PASS dal nuovo host
 - [ ] Burn-in capacity 4 job concorrenti PASS, tempi entro ±20% del baseline
 - [ ] Storage migrato a `/var/lib/ci/`, host Windows in stand-by come rollback
 - [ ] Tutti i timer systemd attivi e schedulati