feat(teams): the slash-command seam, and the first command through it

Phase 7 of TEAMS.md. `api.registerSlashCommands` stops throwing: a module
registers a command's DEFINITION and its HANDLER together, the bot pulls the
definitions over the internal listener and runs none of our code, and the
handler executes here — forced by the bot container having no `modules` volume,
and the right boundary anyway.

Registration validates what Discord would reject as a batch (names, description
lengths, the four option types, required-before-optional), because the bot
registers the whole set in one PUT and a single bad entry costs every command
including the bot's own. Commands are not namespaced under their owner — there
is no dot in Discord's name grammar — so collisions are first-come with the
holder named.

The dispatcher is the access boundary: `linked` has no Discord equivalent, so
the platform-side permission default can only ever be advertising. It resolves
the actor by `auth_providers.kind` rather than the id slug, treats a banned
account as unlinked, bounds a handler under the bot's own timeout, and keeps
`ok` outside the envelope so a handler cannot forge it.

Liveness is asked at both the pull and the dispatch. The registries have no
removal path, so a module an operator disables at runtime would otherwise keep
a live handler behind a command Discord still advertises.

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

bot/src/internal/internal.controller.js

@@ -99,4 +99,26 @@ async function reverseModAction(req, res) {
   }
 }
 
-module.exports = { setConfig, getStatus: getStatusHandler, announce, reverseModAction }
+// POST /internal/refresh-commands — the app's nudge that its registered
+// slash-command set has moved (TEAMS.md §7.1). No body: the bot re-pulls
+// `/internal/commands` and re-registers only if the set actually changed, so the
+// nudge stays a cheap thing the app can send on every module state change.
+//
+// Deliberately its OWN endpoint rather than riding on /internal/config, which
+// carries the decrypted bot token: saying "commands changed" should not require
+// the app to read a secret out of the database.
+//
+// Answers 200 even when disconnected — there is no application to register
+// against until the bot logs in, and `ready` pulls again anyway. A 5xx here
+// would make an ordinary module install look like a failure in the admin panel.
+async function refreshCommands(req, res) {
+  try {
+    const result = await discordManager.refreshCommands()
+    return res.json({ ok: true, ...result })
+  } catch (err) {
+    log.error('refresh-commands failed', { message: err.message })
+    return res.json({ ok: false, error: err.message })
+  }
+}
+
+module.exports = { setConfig, getStatus: getStatusHandler, announce, reverseModAction, refreshCommands }