Update shared Gaia workflows and Sargo development tooling

Fix camera switching and Contacts/SMS activity routing across shared hosts.
Integrate Marketplace installation and native standalone recovery tools,
Bluetooth runtime packages and trusted certificates.

Update English/French READMEs and the shared changelog with tested scope
and remaining radio/audio/Bluetooth limitations. Preview17 remains the
existing APK; no new native image is released.

Validation: shared JavaScript and native Python tests; Android packaging
and payload parity from an isolated publication checkout.

tundra/boot/standalone-mount.sh

@@ -0,0 +1,14 @@
+#!/bin/busybox sh
+# SPDX-License-Identifier: MPL-2.0
+# Mount only the prepared Tundra volume. Never format or guess an old filesystem.
+set -eu
+# VOLUME_CONFIGURATION
+mkdir -p /volume
+blkid "$VOLUME_DEVICE" | grep -F "UUID=\"$VOLUME_UUID\"" >/dev/null
+repaired=0
+e2fsck -p "$VOLUME_DEVICE" || repaired=$?
+test "$repaired" -le 1
+mount -t ext4 -o "$VOLUME_OPTIONS" "$VOLUME_DEVICE" /volume
+test "$(cat /volume/tundra-volume-id)" = "$VOLUME_UUID"
+echo TUNDRA_STANDALONE_VOLUME_READY
+exec /bin/sh /native-root.sh