Honor bread.command.help.open via breadhelp listen

EVENTS.md

@@ -9,14 +9,17 @@ follows.
 
 App id: **`help`**. Transport: `bread-utils`'s `bread_client` module
 (feature `bread-client`) — breadhelp links it directly. Each `emit` is
-its own short-lived connection. There is no long-running command
-subscription.
+its own short-lived connection. Command verbs are only received while
+`breadhelp listen` is running — that process holds the
+`bread.command.help.**` subscription open.
 
 ## Events published (`bread.help.*`)
 
 | Event | Data | When |
 |-------|------|------|
 | `bread.help.opened` | `{ "autostart": bool }` | The main help window is presented (`ApplicationWindow::present`). `autostart` is `true` when that invocation was launched with `--autostart`. |
+| `bread.help.open.done` | `{}` | `bread.command.help.open` was received and `breadhelp` was spawned. This is the command confirmation, not proof the window mapped — the spawned process is the same no-args invocation as SUPER+/. |
+| `bread.help.open.failed` | `{ "error": "<message>" }` | `bread.command.help.open` was received but this binary could not be started. |
 
 Not emitted when:
 
@@ -29,14 +32,36 @@ Not emitted when:
 
 ## Commands honored (`bread.command.help.*`)
 
-None. Opening the help center, starting the tour, and applying one-click
-fixes already exist as local CLI / UI paths. There is no command
-subscription, and no verb is stubbed as a no-op. If breadhelp later grows
-a bus verb that maps to real behavior, add it then.
+These are only received while `breadhelp listen` is running. Publishing a
+command with no subscriber is a silent no-op — that is the documented
+bread convention, not a breadhelp bug.
+
+| Verb | Data | Effect |
+|------|------|--------|
+| `open` | none | Same as running `breadhelp` with no flags: present the main help window (GApplication forwards to an already-running primary instance). Emits `bread.help.open.done` / `.failed`. |
+
+```lua
+bread.spawn(function()
+    bread.emit("bread.command.help.open")
+    bread.wait("bread.help.open.done", { timeout = 5000 })
+end)
+```
+
+### Not implemented: extra verbs
+
+There is no `onboard` / `tour` / `suggest` command verb. Those already
+exist as local CLI flags (`--onboard`, `--tour-event`, `--suggest`).
+If/when a bus verb maps to real extra behavior, add it then — do not
+stub one as a no-op ahead of it.
 
 ## Fail-safe behavior
 
 - If breadd isn't installed or isn't running, `emit` is a silent no-op
-  (`BreadClient::emit` never blocks or errors the caller) — the help
+  (`BreadClient::emit` never blocks or errors the caller) and the
+  command subscription simply never receives anything — the help
   center, tour, and screenshots are entirely unaffected.
-- There is no command subscription to reconnect.
+- If breadd restarts, the command subscription reconnects automatically
+  (`BreadClient::subscribe`'s background thread has its own backoff
+  loop); no restart of `breadhelp listen` is needed.
+- If `breadhelp listen` is not running, commands are a graceful no-op at
+  the bus (no subscriber). The CLI still works.