Remove dead Go types and event code

- Delete unused Grant struct (persona-era, zero references)
- Delete CompositeModelKey (never called)
- Remove dead comment-only type stubs (NoteGraph, ProjectChannel, etc.)
- Remove empty Chat/Channel event sections from route table
- Remove dead chat.typing/channel.typing condition in WS subscriber
- Update bus doc examples and test labels to use real event names

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/events/bus.go

@@ -43,10 +43,10 @@ func (b *Bus) SetBroadcastHook(fn func(Event)) {
 //
 // Patterns:
 //
-//	"chat.message.abc123"  — exact match
-//	"chat.message.*"       — wildcard: matches chat.message.{anything}
-//	"chat.*"               — wildcard: matches chat.{anything}
-//	"*"                    — matches all events
+//	"workflow.assigned.abc123"  — exact match
+//	"workflow.assigned.*"      — wildcard: matches workflow.assigned.{anything}
+//	"workflow.*"               — wildcard: matches workflow.{anything}
+//	"*"                        — matches all events
 func (b *Bus) Subscribe(pattern string, handler Handler) func() {
 	b.mu.Lock()
 	b.seq++