feat: add guided /gw-triage:setup for Jira token

Replaces the manual shell-profile steps in the README: the skill
verifies the token before saving it to ~/.claude/settings.json env,
where Claude Code injects it shell-independently.

skills/triage/SKILL.md

@@ -25,11 +25,12 @@ them in ONE ToolSearch call before Step 0:
    - esegui `/mcp`, seleziona `atlassian` e completa il login nel browser con l'account aziendale
    - poi rilancia `/gw-triage:triage`
 2. Run `test -n "$JIRA_EMAIL" && test -n "$JIRA_API_TOKEN" && echo ok || echo missing`.
-   If `missing`: continue, but tell the user (Italian) that the
-   screenshot cannot be attached automatically and point them to the
-   "Token API Jira" section of the plugin README
-   (`${CLAUDE_PLUGIN_ROOT}/README.md`) — show the 4 token steps inline,
-   once, then proceed.
+   If `missing`: check whether `~/.claude/settings.json` has
+   `env.JIRA_EMAIL`/`env.JIRA_API_TOKEN`. If yes, the session predates
+   the config: tell the user (Italian) to restart Claude Code to enable
+   automatic attachments. If no, tell them the screenshot cannot be
+   attached automatically and that `/gw-triage:setup` configures it in
+   a couple of minutes. Either way, say it once and proceed.
 
 ## Step 1 — Input