mavweb: /events gets its page chrome (V-578)

Found by the mavweb sweep. The key was in the sidebar and absent from the chrome
table, so the tab read lowercase and the icon fell through to the default while
the link said Intake. Title now matches the link, and i-download is the closest
symbol ethos-icons.svg has to an inbox.

--no-verify: the pre-commit hook refuses master, and this unattended run merges
to master by the owner's instruction.

cmd/mavweb/shell.go

@@ -90,6 +90,7 @@ var pageChrome = map[string]struct{ Title, Icon string }{
 	"reminders":     {"Reminders", "i-calendar"},
 	"routines":      {"Routines", "i-repeat"},
 	"morning":       {"Morning Routines", "i-calendar"},
+	"events":        {"Intake", "i-download"},
 	"chat":          {"Chat", "i-message"},
 	"voice":         {"Voice", "i-mic"},
 	"ecosystem":     {"Ecosystem", "i-grid"},