Commit log (v0.2.70..HEAD)

2d20341f chore(release): 0.2.71 [skip ci] (GitHub Action)
acaba1d6 ci(issue-triage): prime Rust toolchain and cache codex-rs/target so agent builds via ./build-fast.sh are incremental (James Peter)
ac994e87 fix(tui/onboarding): apply themed background to auth picker surface (James Peter)
3e4a648f fix(ci/upstream-merge): avoid PR 422 by validating head branch and using owner:branch; add Rust cache + toolchain for incremental builds like ./build-fast.sh (James Peter)
c4e586cf style(login/success): fix background + theme variables (James Peter)
d43eb23e fix(login): remove /oauth2/token fallback; adopt upstream-visible request shape (James Peter)
93f6b4ac docs(changelog): update for v0.2.70 [skip ci] (GitHub Action)