v0.17.0

Two community fixes, both for bugs that were invisible until someone hit them.

• Fix: FaceID could go silent on MQTT without any sign of it (#11, fixed by @zlowred in
  #12). self.client was assigned after connect() and loop_start(). A broker that
  answers fast enough — typically a local one without authentication — fired _on_connect
  on the network thread before that assignment landed, and _publish_discovery hit
  None.publish. The exception killed the paho thread.
• The failure mode is the nasty part: the service keeps running, the web UI responds, faces
  are still recognised — and nothing is ever published to MQTT again. If your sensors
  went quiet for no apparent reason, this was a candidate. The only visible trace was a
  traceback at startup.
• Hardened against the whole class of bug. Any exception in a paho callback takes down
  the network thread the same way, so both callbacks now catch and log instead of letting
  it propagate. A future bug in message handling will cost one event, not the connection.
• Fix: two people with non-Latin names collided (#10, fixed by @egmen in #9). slugify()
  stripped everything outside [a-z0-9], so "Макс" became empty and fell back to the
  literal folder person. The second such name mapped to the same folder: the UI said
  "Person created" and nothing appeared.
• Slugs now stay ASCII but get a stable name-derived suffix when a script has no ASCII form,
  and remaining collisions are disambiguated instead of silently reusing an existing person.
  Display names keep their original Unicode. Verified against a 14-person gallery: no
  existing slug changes, so nothing moves on upgrade.
• That PR also brought the repo's first unit tests, now part of CI.
• rename() now compares names the same way create_person() does. It used plain
  casefold(), so two names that differ only in Unicode composition — visually identical —
  could end up as separate people depending on which path created them.