Add EPI-Support monitoring & analytics platform

Internal Flask app that monitors the epi-helpdesk.zammad.com tickets via
the Zammad API, deployable as a systemd service behind Apache under
/episupport.

Features:
- Poller: session-login API sync, snapshot diff to detect agent changes
  (status, owner, priority, closures, new replies); email notifications
- Dashboard: ticket overview with sorting, "not closed" filter and
  highlighting of tickets with unconfirmed changes; per-item and bulk
  "mark as read"
- Analytics: KPIs, response/resolution times, monthly SVG trend chart,
  distributions (status/priority/group/agent), Excel export
- Conversation view: full per-ticket thread cached in the DB (avoids
  proxy timeouts), inline image attachments, safe HTML-to-text rendering
- Write actions: reply to tickets and create new tickets with a
  confirmation step and attachment upload (incl. clipboard paste);
  self-triggered actions are synced back so they aren't flagged as changes
- Local timezone display (Europe/Berlin) for all timestamps

Includes deploy tooling: setup.sh, systemd units and Apache config.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/episupport-apache.conf

@@ -9,7 +9,7 @@
 
 <Location /episupport>
     ProxyPreserveHost On
-    ProxyPass        http://127.0.0.1:8071/
+    ProxyPass        http://127.0.0.1:8071/ timeout=120
     ProxyPassReverse http://127.0.0.1:8071/
 
     # Damit die App ihre Links korrekt mit /episupport-Präfix erzeugt