Guidepoint: Fix - Strip internal build paths from release binaries

[cmgustavo]

Release iOS/Android binaries embedded absolute build-machine paths and developer usernames (e.g. /Users/<dev>/dev/bitpay-app/...) via __FILE__/#file macro strings and debug info in compiled native code.
Stripping does not remove the macro strings, so add a Clang path-prefix-map that rewrites the repo root to "./" at compile time (computed per-build-machine; nothing absolute committed).

• ios/Podfile: append -ffile-prefix-map (C/C++/ObjC) and -file-prefix-map (Swift) to all Release pod targets in post_install.
• android/build.gradle: subprojects block appends -ffile-prefix-map to cppFlags/cFlags on each module's Release CMake build (state.executed guard avoids the already-evaluated react-native-gradle-plugin; Release-only).

Verification:

• iOS: grep -ra '/Users' Payload/BitPayApp.app | strings | egrep '^/Users/.+/.+' | awk -F/ '{print $3}' | sort -u
• Android: unzip -p base.apk | strings | grep '/Users/' | sort -u