Switch to Noctalia v5 and fix niri startup

Fix Mod+T bind (one action per bind), launch noctalia v5 from autostart,
port keybinds to `noctalia msg`, add config.toml, changelog and docs.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -40,7 +40,8 @@ This installs ansible if missing, then runs the playbook. Tasks are split by cat
 Edit the relevant split file, not `config.kdl` itself.
 
 ### Noctalia (desktop shell / bar)
-All settings live in `noctalia/settings.json` (JSON, edited by the Noctalia GUI or directly). Colorschemes are in `noctalia/colorschemes/` and plugins in `noctalia/plugins/`.
+Runs **Noctalia v5** (`noctalia`, native). Config is `noctalia/config.toml` (TOML, hot-reloaded); validate with `noctalia config validate`.
+`noctalia/settings.json` is the legacy v4 config. See `docs/noctalia-v5.md` for details and `CHANGELOG.md` for history.
 
 ### Neovim
 Uses **LazyVIM** framework. Entry point is `nvim/init.lua` which bootstraps lazy.nvim via `nvim/lua/config/lazy.lua`.