Add Telegram notification script for sending build artifacts

scripts/notify_telegram.sh sends a file (e.g. the debug APK) to a
Telegram chat via Bot API sendDocument. Reads TELEGRAM_BOT_TOKEN and
TELEGRAM_CHAT_ID from .telegram.env (gitignored, real credentials
never committed) or the environment. Verified end-to-end: sent the
current debug APK and confirmed delivery.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/notify_telegram.sh

@@ -0,0 +1,37 @@
+#!/bin/sh
+# Sends a file (e.g. a freshly built APK) to a Telegram chat via a bot.
+# Usage: scripts/notify_telegram.sh <path-to-file> ["optional caption"]
+#
+# Reads TELEGRAM_BOT_TOKEN and TELEGRAM_CHAT_ID from .telegram.env
+# (gitignored) at the repo root, or from the environment if already set.
+
+set -eu
+
+SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
+REPO_ROOT=$(cd "$SCRIPT_DIR/.." && pwd)
+ENV_FILE="$REPO_ROOT/.telegram.env"
+
+if [ -f "$ENV_FILE" ]; then
+    # shellcheck disable=SC1090
+    . "$ENV_FILE"
+fi
+
+if [ -z "${TELEGRAM_BOT_TOKEN:-}" ] || [ -z "${TELEGRAM_CHAT_ID:-}" ]; then
+    echo "TELEGRAM_BOT_TOKEN / TELEGRAM_CHAT_ID not set (checked $ENV_FILE and environment)." >&2
+    exit 1
+fi
+
+FILE_PATH="${1:?Usage: notify_telegram.sh <path-to-file> [caption]}"
+CAPTION="${2:-$(basename "$FILE_PATH")}"
+
+if [ ! -f "$FILE_PATH" ]; then
+    echo "File not found: $FILE_PATH" >&2
+    exit 1
+fi
+
+curl -sS -F "chat_id=${TELEGRAM_CHAT_ID}" \
+    -F "document=@${FILE_PATH}" \
+    -F "caption=${CAPTION}" \
+    "https://api.telegram.org/bot${TELEGRAM_BOT_TOKEN}/sendDocument" \
+    | tee /dev/stderr \
+    | grep -q '"ok":true'