fix(example): fix device detection in build.sh on Linux

[mengh04]

Problem

example/build.sh checks for a connected Android device/emulator with:

adb devices 2>/dev/null | grep -cE '\t(device|emulator)'

On Linux, GNU grep does not interpret \t as a tab character in -E mode: it emits grep: warning: stray \ before t and matches the literal character t instead. Since adb devices output separates the serial from the state with an actual TAB character, the pattern never matches — so the script always reports ✘ No connected Android device found even when a device/emulator is connected.

(The script was developed on macOS, where BSD grep accepts \t in -E mode, so the bug is Linux-only.)

Fix

Replace \t with the POSIX character class [[:blank:]], which matches a space or tab on both BSD grep (macOS) and GNU grep (Linux):

device_count=$(adb devices 2>/dev/null | grep -cE '[[:blank:]](device|emulator)') || true

Test plan

• adb devices shows a connected device (fbaa461b1023 device)
• ./build.sh android --release now proceeds past the device check to Installing & launching on Android