Rename the crate, binary, logger/syslog tags, internal types, share/ path, and all Nix/flake/README references from sessiond-dinit to sessiond-hooks. The binary and Dhall config are unchanged in shape: one process still applies a single `Context -> { init, args }` config per session. Move multiplicity to Nix: `services.sessiond-hooks` is now an attrset of named instances, each spawning an independent `sessiond-hooks` process (finit service `sessiond-hooks-<name>`) with its own config + Prelude dir. Defining an entry makes it live; there is no enable toggle. Drop the hardcoded dinit from the module's systemPackages now that hooks are init-agnostic. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>