recipe: duckdb 1.5.4

[ndonkoHenri]

Adds duckdb 1.5.4 — the in-process analytical (OLAP) database — for iOS and Android.

Closes flet-dev/flet#3881.

Recipe shape

scikit-build-core + CMake (C++11), no patches. The _duckdb pybind11 extension is the whole engine; duckdb + ICU + all third-party are vendored in the sdist, so there are no external native dependencies and no mandatory runtime deps:

• requirements.build: [cmake, ninja] (scikit-build-core / pybind11 / setuptools_scm come from the package's own build-system.requires).
• Android: flet-libcpp-shared host dep (the C++ runtime), ANDROID_STL=c++_shared, and 16 KB-alignment linker flags; FindPython via CROSS_VENV_PYTHON.
• iOS: Unix Makefiles generator (the ninja pip package crashes on the iOS crossenv Python) + CMAKE_SYSTEM_NAME=iOS; same CROSS_VENV_PYTHON FindPython.

It's a heavy package (the _duckdb.so is ~15–18 MB/arch).

Tested

• Full matrix builds green: Android (arm64-v8a, armeabi-v7a, x86, x86_64) + iOS (arm64 device, arm64 sim, x86_64 sim), Python 3.12 — no patches, 32-bit arches build cleanly.
• On-device (Android arm64 emulator + iOS simulator): import duckdb loads the C++ engine and a real in-memory CREATE/INSERT/SELECT + aggregate round-trip returns correct results.