Rename app from chat to neoirc, binary to neoircd (closes #46)

- Rename Go module path: git.eeqj.de/sneak/chat -> git.eeqj.de/sneak/neoirc
- Rename binary: chatd -> neoircd, chat-cli -> neoirc-cli
- Rename cmd directories: cmd/chatd -> cmd/neoircd, cmd/chat-cli -> cmd/neoirc-cli
- Rename Go package: chatapi -> neoircapi
- Update Makefile: binary name, build targets, docker image tag, clean target
- Update Dockerfile: binary paths, user/group names, ENTRYPOINT
- Update .gitignore and .dockerignore
- Update all Go imports and doc comments
- Update default server name fallback: chat -> neoirc
- Update web client: localStorage keys, page title, default server name
- Update all schema $id URLs and example hostnames
- Update README.md: project name, binary references, examples, directory tree
- Update AGENTS.md: build command reference
- Update test fixtures: app name and channel names

internal/handlers/api.go

@@ -229,7 +229,7 @@ func (hdlr *Handlers) deliverMOTD(
 	serverName := hdlr.params.Config.ServerName
 
 	if serverName == "" {
-		serverName = "chat"
+		serverName = "neoirc"
 	}
 
 	if motd == "" {