Rename azos-core station suite to desktop; move discord out to azos/features

Mirrors the azos-core change: station is renamed desktop (its apps are
generically useful on any machine, work included), discord moves to its
own standalone azos/features/discord (personal-only, so it lives in the
azos project rather than azos-core), and azos-emacs-station becomes
azos-emacs-desktop in lauretta's emacs config to match.

AGENTS.md

@@ -128,7 +128,7 @@ All features follow this flake-parts registration pattern:
 
 ### Naming Conventions
 - Option paths: `azos.<module-name>.<option>`
-- Module names: kebab-case (`git-config`, `station`)
+- Module names: kebab-case (`git-config`, `desktop`)
 - Feature directories: kebab-case, one `default.nix` per feature
 - Variables: kebab-case
 
@@ -174,8 +174,13 @@ Top-level suites group related features (defined in `azos-core/`):
 - `azos.suites.base` — base packages and config
 - `azos.suites.editor` — editor tools
 - `azos.suites.dev` — development tools
-- `azos.suites.station` — desktop applications
-- `azos.suites.exwm` — EXWM window manager
+- `azos.suites.desktop` — desktop session plumbing (flameshot, dunst, keyboard layout) plus generally-useful apps (browser, libreoffice, zoom, spotify, gimp, whatsapp). Shared, lives in azos-core — wanted on any GUI machine, work included.
+- `azos.suites.exwm` — EXWM window manager, depends on `desktop`
+
+Machine-specific, personal-only apps (steam, discord) are **not** part of any azos-core
+suite — they live as standalone features directly in `azos/features/`, imported only on
+machines that want them (e.g. `azos/features/discord`, `azos/features/steam`), since any
+such machine already uses the `azos` project rather than a different downstream repo.
 
 The machine suite (`azos.suites.lauretta`) enables the relevant suites for this machine.