feat(events): give a session an event envelope carrying run lifecycle - #794

🟢 commit (${\color{blue}8c0a23f}$) doc(events): drop the claim that no second run id travels

🟢 commit (${\color{blue}85f0a05}$) feat(events): carry usage on every terminal lifecycle event

🟢 commit (${\color{blue}fa9af6f}$) feat(events): let a start name the run it continues

🟢 commit (${\color{blue}53e19a1}$) doc(events): say what a false from follows() covers

🟢 commit (${\color{blue}778eaa4}$) fix(events): read a null liveness as the default

🟢 commit (${\color{blue}2a25276}$) feat(events): read an unknown variant as unknown rather than failing

🟢 commit (${\color{blue}5db77be}$) refactor(cli): use the shared duration_ms serde module

🟢 commit (${\color{blue}1e7fd93}$) refactor(events): share timestamp, sequence number, and duration_ms

🟢 commit (${\color{blue}58337b4}$) feat(events): refuse empty and nil identifiers

🟢 commit (${\color{blue}a153df9}$) feat(events): give a session an event envelope carrying run lifecycle