recipe: oracledb 4.0.1

[ndonkoHenri]

Adds python-oracledb 4.0.1 (official Oracle Database driver) for iOS and Android.

Closes flet-dev/flet#3249. Also supersedes the cx_Oracle request (flet-dev/flet#3381), which is infeasible on mobile (it requires the proprietary Oracle Instant Client); oracledb's default thin mode needs no Oracle client libraries.

Recipe shape

Plain Cython C-extension, no patches, no flet-lib* dependency. python-oracledb compiles four Cython extensions (base_impl, thin_impl, thick_impl, arrow_impl), and bundles all its native code in the sdist — ODPI-C (for thick mode) and nanoarrow (for Arrow dataframes) — so there's no external native library to build or link.

Runtime deps cryptography (already on pypi.flet.dev) and typing_extensions (pure-Python) come from the wheel metadata and resolve at app-build time.

Thin vs thick mode

The default thin mode is a pure-socket implementation of Oracle Net — no Oracle client libraries required, so it works on mobile. thick_impl.so is imported at package load (oracledb/__init__.py) and builds/loads fine without the Instant Client (ODPI-C dlopens it lazily, only on init_oracle_client()), so thick mode is simply unavailable on mobile while thin mode — the supported path — works.

Tested

• Full matrix builds green (zero patches): Android arm64-v8a/armeabi-v7a/x86/x86_64 and iOS arm64 (device) / arm64 (simulator) / x86_64 (simulator), Python 3.12.
• On-device against a LIVE database (Android arm64 emulator + iOS simulator): import oracledb loads all four Cython extensions, is_thin_mode() is True, cryptography loads, and a real thin-mode round-trip — Oracle Net handshake + O5LOGON crypto auth + SELECT 'hello-from-flet', SYSDATE FROM dual — succeeds against Oracle Database Free 23ai (server 23.26.2.0.0), returning the expected row on both platforms.