feat: rename info to status, add /status slash command

Rename session info endpoint from /sessions/:id/info to /sessions/:id/status
and update frontend tab label accordingly. Add /status slash command that
displays current session metrics (message count, context usage, cache hit
rate, used skills) as formatted text in any channel.

internal/db/sqlc/session_info.sql.go

@@ -42,6 +42,23 @@ func (q *Queries) GetLatestAssistantUsage(ctx context.Context, sessionID pgtype.
 	return input_tokens, err
 }
 
+const getLatestSessionIDByBot = `-- name: GetLatestSessionIDByBot :one
+SELECT s.id
+FROM bot_sessions s
+WHERE s.bot_id = $1
+  AND s.type = 'chat'
+  AND s.deleted_at IS NULL
+ORDER BY s.updated_at DESC
+LIMIT 1
+`
+
+func (q *Queries) GetLatestSessionIDByBot(ctx context.Context, botID pgtype.UUID) (pgtype.UUID, error) {
+	row := q.db.QueryRow(ctx, getLatestSessionIDByBot, botID)
+	var id pgtype.UUID
+	err := row.Scan(&id)
+	return id, err
+}
+
 const getSessionCacheStats = `-- name: GetSessionCacheStats :one
 SELECT
   COALESCE(SUM((m.usage->>'inputTokens')::bigint), 0)::bigint AS total_input_tokens,