fix: review findings — env-var netrc write hygiene, network-vs-auth errors, installer collision guard, docs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skills/triage/SKILL.md

@@ -66,8 +66,10 @@ with user text on the command line.
          --netrc-file ~/.config/gw-triage/netrc \
          <site>/rest/api/2/myself
 
-   Anything but `200` → STOP (Italian): token scaduto o revocato,
-   rilancia `$setup`.
+   - `401`/`403` → STOP (Italian): token scaduto o revocato,
+     rilancia `$setup`.
+   - anything else → STOP (Italian): problema di rete verso Jira, non
+     di credenziali — riprova più tardi.
 
 ## Step 1 — Input