caps: implement first capability response (kitty keyboard)

Signed-off-by: Tim Culverhouse <[e-mail]>

src/Tty.zig

···
                         vx.postEvent(.paste_end);
                     }
                 },
+                .cap_kitty_keyboard => {
+                    if (@hasField(EventType, "cap_kitty_keyboard")) {
+                        vx.postEvent(.cap_kitty_keyboard);
+                    }
+                },
             }
         }
     }

src/event.zig

···
     focus_out,
     paste_start,
     paste_end,
+    cap_kitty_keyboard,
 };

src/main.zig

···
 
 pub const Key = @import("Key.zig");
 pub const Winsize = @import("Tty.zig").Winsize;
+pub const Event = @import("event.zig").Event;
 
 pub const widgets = @import("widgets/main.zig");
 

src/parser.zig

···
                                 }
                             },
                             'u' => blk: {
-                                if (seq.private_indicator) |_| {
+                                if (seq.private_indicator) |priv| {
                                     // response to our kitty query
                                     // TODO: kitty query handling
+                                    if (priv == '?') {
+                                        return .{
+                                            .event = .cap_kitty_keyboard,
+                                            .n = i + 1,
+                                        };
+                                    }
+
                                     log.warn("unhandled csi: CSI {s}", .{input[start + 1 .. i + 1]});
                                     return .{
                                         .event = null,