v0.1.2: Fix TestFlight upload rejection: iOS build number was stuck at 0

TestFlight upload failed with ENTITY_ERROR.ATTRIBUTE.INVALID.DUPLICATE:
"The bundle version must be higher than the previously uploaded version"
(previousBundleVersion: 0). PlayerSettings' iOS buildNumber (-> IPA's
CFBundleVersion) was literally 0 and never incremented, so every future
build/upload would collide with whatever Apple already has on record for
"0" - Apple requires each upload's CFBundleVersion to be strictly higher
than the last, so 0 could never succeed again regardless of how many times
it's rebuilt and re-uploaded.

This has to be fixed before Unity Cloud Build signs the IPA, not after -
editing CFBundleVersion post-build (e.g. in the GitHub Actions upload step)
would invalidate the code signature since Info.plist is part of the sealed
resources the signature covers, and this pipeline has no signing
certs/profile to re-sign with, only an App Store Connect API key for
uploading.

Bumped to 1 (verified on disk, not just via the tool's own read-back - it's
lied about persisting PlayerSettings changes before). A new Unity Cloud
Build run is still needed to actually produce an IPA with this baked in.
For future releases, either bump this again each time or check whether
Unity Cloud Build's advanced settings has an auto-increment build number
option.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>