### Projects (first-class delivery containers)
- A project is a **stable generated id** — the `[projects.<id>]` registry key in
`tix.toml` — with a mutable display `name`; every association stores the **id**,
so a rename changes the label only and never re-keys anything (C-002)
- `tix project create <name> [--description --status --lead --start-date --due-date]`,
`tix project edit <id> [--name …]` (label only), `tix project list` (a row per
project: id, name, member count), `tix project show <id>` (record, progress,
health counts and members), `tix project delete <id>` (removes the registry
entry **only** — issues keep their references as diagnosable
`missing_project_reference` findings, never deleted)
- Associate and dissociate: `tix project add <id> <sel>…`,
`tix project remove <id> <sel>…`, `tix project bulk-add <id> <sel>…`,
`tix create --projects <id,id>`, `tix edit <sel> --add-project <id>` /
`--remove-project <id>` / `--projects ""` (clears every association). An issue
may belong to **multiple** projects
- Filter, group and sort by project: `tix search "project:<id>"`, `tix list
--project <id>`, `tix list --group project` / `--sort project` and
`tix status --group project`. A single membership buckets by project id, several
as `(multiple projects)`, and none as `(no project)`. The TUI exposes the same
through `F10` (Portfolio) and the filter modal's project row