iOS ships CPython 3.14.6 while every other target ships 3.14.7 #47

Reported by the PMM build session, confirmed: the acquired iOS framework is BeeWare Python-Apple-support 3.14-b10 (python-checksums.properties ios-3.14-b10), and its headers say PY_VERSION "3.14.6" (extracted/ios/Python.xcframework/ios-arm64/include/python3.14/patchlevel.h), while pythonVersion=3.14.7 everywhere else. Bytecode is compatible (same minor), but version reporting, patch-level fixes and the "one interpreter version" assumption (and pypackpack's pinned interpreter set) break on iOS.

Find a 3.14.7 iOS build (python.org's official iOS XCframework releases if they exist for 3.14.7, or a newer BeeWare build), pin its SHA-256, and switch; if none exists, fail the build's version check loudly instead of silently shipping 3.14.6, and record it in docs/platforms/python-version-acquisition.md.

Completion: a test asserts the acquired iOS headers' PY_VERSION equals pythonVersion (and the same for every other target), red today.