fix(examples): use tty.writer() flush call in text_view

[nowaymyname27]

Summary

• update examples/text_view.zig to call tty.writer().flush() instead of tty.writer.flush()
• fixes the Zig 0.15.2 compile-time API mismatch in the text_view example

Testing

• manually reproduced failure before fix (no field named 'writer' in struct 'tty.PosixTty')
• zig build example -Dexample=text_view now reaches runtime and fails opening /dev/tty in this non-interactive environment (expected here)

[rockorager]

Thanks!