feat: initial whatsmeow bot with command handler and context helpers

Core framework (Handler, Command, Default muxer) in core/ package.
Command self-registration via init() with blank imports in cmds/.
Context helpers (send, reply, download, upload) in context/ package.
Permission system with GROUP_ONLY / PRIVATE_ONLY checks.
WhatsApp client configured as Safari with history sync disabled.

go.mod

@@ -0,0 +1,35 @@
+module neo
+
+go 1.25.5
+
+require (
+	github.com/mattn/go-sqlite3 v1.14.47
+	github.com/mdp/qrterminal/v3 v3.2.1
+	go.mau.fi/whatsmeow v0.0.0-20260630180629-b572e5bcb92b
+)
+
+require (
+	filippo.io/edwards25519 v1.2.0 // indirect
+	github.com/beeper/argo-go v1.1.2 // indirect
+	github.com/coder/websocket v1.8.15 // indirect
+	github.com/elliotchance/orderedmap/v3 v3.1.0 // indirect
+	github.com/gabriel-vasile/mimetype v1.4.13 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/joho/godotenv v1.5.1 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/petermattis/goid v0.0.0-20260330135022-df67b199bc81 // indirect
+	github.com/rs/zerolog v1.35.1 // indirect
+	github.com/vektah/gqlparser/v2 v2.5.27 // indirect
+	go.mau.fi/libsignal v0.2.2 // indirect
+	go.mau.fi/util v0.9.10 // indirect
+	golang.org/x/crypto v0.53.0 // indirect
+	golang.org/x/exp v0.0.0-20260611194520-c48552f49976 // indirect
+	golang.org/x/net v0.56.0 // indirect
+	golang.org/x/sync v0.21.0 // indirect
+	golang.org/x/sys v0.46.0 // indirect
+	golang.org/x/term v0.44.0 // indirect
+	golang.org/x/text v0.38.0 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
+	rsc.io/qr v0.2.0 // indirect
+)