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/rootfs/etc/cont-init.d/02-timezone.sh

@@ -1,27 +0,0 @@
-#!/usr/bin/with-contenv bashio
-# shellcheck shell=bash
-set -euo pipefail
-
-# Use timezone defined in add-on options
-bashio::log.info "Setting timezone..."
-TZ_VALUE="$(bashio::config 'TZ' || true)"
-TZ_VALUE="${TZ_VALUE:-Europe/Paris}"
-
-if [ ! -f "/usr/share/zoneinfo/${TZ_VALUE}" ]; then
-    bashio::log.warning "Invalid timezone '${TZ_VALUE}'. Falling back to Europe/Paris."
-    bashio::log.warning "See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for valid values."
-    TZ_VALUE="Europe/Paris"
-fi
-
-# Apply timezone to the container
-ln -sf "/usr/share/zoneinfo/${TZ_VALUE}" /etc/localtime
-echo "${TZ_VALUE}" > /etc/timezone
-export TZ="${TZ_VALUE}"
-sed -i "1a TZ=\"${TZ_VALUE}\"" /etc/services.d/*
-
-# Update s6 container environment so child processes inherit the timezone
-if [ -d /var/run/s6/container_environment ]; then
-    echo "${TZ_VALUE}" > /var/run/s6/container_environment/TZ
-fi
-
-bashio::log.notice "Timezone set to: ${TZ_VALUE}"