feat: implement agent-notify CLI with hooks and tmux passthrough

Add OSC 777 notification sender, Cursor/Claude hook adapters,
config/install commands, and README for Ghostty + tmux setup.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/context/meta_test.go

@@ -0,0 +1,26 @@
+package context
+
+import "testing"
+
+func TestRenderTitle(t *testing.T) {
+	meta := Meta{Agent: "Cursor", Context: "myapp"}
+	got := Render("{agent} — {context}", meta)
+	want := "Cursor — myapp"
+	if got != want {
+		t.Fatalf("got %q want %q", got, want)
+	}
+}
+
+func TestContextFromCWD(t *testing.T) {
+	meta := Meta{Agent: "Claude", CWD: "/home/user/code/myapp"}
+	if meta.ResolveContext("") != "myapp" {
+		t.Fatalf("got %q", meta.ResolveContext(""))
+	}
+}
+
+func TestContextPrefersWindow(t *testing.T) {
+	meta := Meta{Agent: "Claude", CWD: "/home/user/code/myapp"}
+	if meta.ResolveContext("tmux-win") != "tmux-win" {
+		t.Fatalf("expected window name")
+	}
+}