D292 - the native title gets its own id, distinct from the package

D287 had the native title reuse the package's id, so the two artifacts were one app. That is right when only one is ever installed, and wrong the moment both are: the ps4 package and the ps5 native title each register under their title id, and a shared id makes the second install collide with the first (observed - a package install of OBSC00001 claimed /user/app/OBSC00001 as a download-stub and a native title of the same id could not take it).

So data/identity.toml now carries two ids: content_id for the package (build-pkg.sh) and content_id_native for the native title (build-native.sh). Each build derives its own title id from its own content id - OBSC00001 for the package, OBSC00002 for the native title - so the two are distinct and can be installed side by side for A/B testing. Both still live in the one file; neither id is written twice (D288 holds - the fix there was one home, not one id).

The uniqueness is obSCEne's, not selfish's, and deliberately so. The natural request is to have selfish emit a different id for native than for pack. It must not: selfish is a generic tool that takes the id as an argument and has to emit exactly that id, and a tool that silently varied it would be inventing identity - the one thing the provenance rule forbids, and a miserable thing to debug when a title registers under an id nobody set. So obSCEne derives the two ids and hands each to selfish explicitly; selfish stays faithful.

The sed readers do not cross-match: ^content_id[[:space:]]*= stops at the _ in content_id_native, and ^content_id_native needs the suffix the plain line lacks. Verified: the native build yields titleId OBSC00002, the package reader yields OBSC00001.