feat(wavelog): push station frequency/mode to Wavelog per operator

Add a CAT integration so the station's current frequency and mode are
reported to each operator's personal Wavelog logbook via Wavelog's radio
API (POST <baseUrl>/index.php/api/radio).

- New plugin rms.wavelog.cat (capability logging.cat.publish): posts
  {key, radio, frequency, mode}. Base URL / radio name come from plugin
  settings or env (WAVELOG_BASE_URL, WAVELOG_RADIO_NAME); no secrets in repo.
- Core hook in the OpenWebRX band-select flow pushes centerFreqHz + startMod
  for the active operator, best-effort (never breaks the band change).
- Per-user Wavelog API key stored on the user record; PUT /v1/me/wavelog-key
  to set it, returned by GET /v1/me and the OpenWebRX session issue response.
- UI: Wavelog API key field in the OpenWebRX panel (visible when generating
  the session link), with i18n (de/en).
- Docs, .env.example entries, and a unit test for the mode mapping.

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

public/i18n/de.json

@@ -52,6 +52,10 @@
     "OpenWebRX laden": "OpenWebRX laden",
     "SDR oeffnen": "SDR oeffnen",
     "Session Key (Ticket):": "Session Key (Ticket):",
+    "Wavelog API Key (Rig-Key)": "Wavelog API Key (Rig-Key)",
+    "Key speichern": "Key speichern",
+    "Frequenz und Mode der Station werden beim Bandwechsel an dein Wavelog-Logbuch gesendet.": "Frequenz und Mode der Station werden beim Bandwechsel an dein Wavelog-Logbuch gesendet.",
+    "Wavelog API Key gespeichert.": "Wavelog API Key gespeichert.",
     "Reservierungen": "Reservierungen",
     "Naechsten Slot reservieren": "Naechsten Slot reservieren",
     "SWR Uebersicht": "SWR Uebersicht",