terminal: improve some debug logging

src/terminal/Parser.zig

@@ -159,7 +159,10 @@ pub const Action = union(enum) {
                     const value = @field(self, u_field.name);
                     switch (@TypeOf(value)) {
                         // Unicode
-                        u21 => try std.fmt.format(writer, "'{u}'", .{value}),
+                        u21 => try std.fmt.format(writer, "'{u}' (U+{X})", .{ value, value }),
+
+                        // Byte
+                        u8 => try std.fmt.format(writer, "0x{x}", .{value}),
 
                         // Note: we don't do ASCII (u8) because there are a lot
                         // of invisible characters we don't want to handle right

src/terminal/stream.zig

@@ -154,7 +154,7 @@ pub fn Stream(comptime Handler: type) type {
                 else
                     log.warn("unimplemented invokeCharset: {x}", .{c}),
 
-                else => log.warn("invalid C0 character, ignoring: {x}", .{c}),
+                else => log.warn("invalid C0 character, ignoring: 0x{x}", .{c}),
             }
         }