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>

.env.example

@@ -86,3 +86,10 @@ MICROHAM_PTT_DOWN_CMD=
 MICROHAM_PTT_UP_CMD=
 OPENWEBRX_ACCESS_POLICY_FILE=./data/openwebrx-access-policy.txt
 OPENWEBRX_PERSISTENT_USERS_FILE=./data/openwebrx-persistent-users.txt
+# rms.wavelog.cat: push current frequency/mode to Wavelog (CAT radio API).
+# Base URL of the Wavelog instance (no trailing slash). Leave empty to disable.
+WAVELOG_BASE_URL=
+# Radio name shown in Wavelog's Radios list.
+WAVELOG_RADIO_NAME=RMS Remote
+# HTTP timeout for the Wavelog API call (ms).
+WAVELOG_TIMEOUT_MS=8000