Phase 1 of deepening the HookSession status machine. The 5 settled
HookProcessStatus values (available/connecting/loaded/online/disconnected)
were hand-derived from (injected,connected,loggedIn,wasLoggedIn) at ~6
call sites in hook-session.ts. Extract that truth table into a pure
statusFor() in hook-status.ts so it has one source of truth and a
mutation-tight exhaustive table test. loading/error stay out-of-band.
Not yet wired into hook-session (phase 2).
DrSmoothl