birdnet-pipy: remove TZ option — timezone auto-derived from station location

The app derives its timezone from station lat/lng via timezonefinder
(Settings → Location in the Web UI), so a separate addon-level TZ only
ever created mismatch with the UI-derived zone. All app-facing timestamps
(dashboard, API, DB) and Python service stdout (api/main/birdnet) already
honor the UI zone via logging_config.py's formatter, and the frontend log
viewer re-converts Icecast timestamps on read.

Net effect in the HA addon log pane: Python services still show the
correct local time; only Icecast's raw stdout now prints in UTC (accepted
trade for a single source of truth). Deletes
rootfs/etc/cont-init.d/02-timezone.sh added in 0.5.6-2.

Also cleans up the options YAML in DOCS.md/README.md: drops
RECORDING_MODE and RTSP_URL (never wired — app reads them from
user_settings.json), drops http_stream from the modes list, and moves
STREAM_BITRATE under an env_vars: example since it's honored by
start-icecast.sh but not a schema option.

Bumped to 0.6.3-2 (addon-only, no upstream app change).

birdnet-pipy/config.yaml

@@ -73,7 +73,6 @@ name: BirdNET-PiPy
 options:
   env_vars: []
   ICECAST_PASSWORD: ''
-  TZ: Europe/Paris
   data_location: /config/data
 panel_icon: mdi:bird
 ports:
@@ -85,7 +84,6 @@ schema:
     - name: match(^[A-Za-z0-9_]+$)
       value: str?
   ICECAST_PASSWORD: str?
-  TZ: str?
   certfile: str?
   cifsdomain: str?
   cifspassword: str?
@@ -97,4 +95,4 @@ schema:
   ssl: bool?
 slug: birdnet-pipy
 url: https://github.com/alexbelgium/hassio-addons/tree/master/birdnet-pipy
-version: "0.6.3"
+version: "0.6.3-2"