fix(setup): import infotext_utils instead of removed legacy alias

[Gunther-Schulz]

Summary

scripts/iib_setup.py imports the renamed-and-now-removed
modules.generation_parameters_copypaste alias, which causes the
extension to fail at script load on current Stable Diffusion WebUI
Forge Classic — the IIB tab silently disappears from the UI.

Background

• modules.generation_parameters_copypaste was renamed to
  modules.infotext_utils in A1111 in
  003b91f0
  (2024-01-01). A sys.modules["modules.generation_parameters_copypaste"] = …
  alias was added in modules/infotext_utils.py for back-compat.
• Forge Classic dropped that alias in commit
  e40900cd
  on 2026-05-05 ("yeet — 1.8.0 was 2 years ago").
• After that change, from modules import … generation_parameters_copypaste as send
  raises ImportError: cannot import name 'generation_parameters_copypaste' from 'modules' (unknown location),
  so neither on_ui_tabs nor on_app_started get registered, and IIB
  becomes invisible to the user.

Fix

Single-line change in scripts/iib_setup.py:

-from modules import script_callbacks, generation_parameters_copypaste as send
+from modules import script_callbacks, infotext_utils as send

infotext_utils exposes the same ParamBinding and
register_paste_params_button symbols used a few lines below. On
A1111 and older Forge releases the legacy alias still resolves to the
same module, so this is a strict superset of the previous behaviour:
it works on every WebUI variant that has infotext_utils (which is
all of them since 2024), and on no variant does it regress.

Test plan

• Reproduced the silent tab-missing behaviour on Forge Classic
  cd2490a8 (2026-05-07).
• Verified that from modules import infotext_utils succeeds in
  Forge Classic's runtime.
• Verified infotext_utils.ParamBinding and
  infotext_utils.register_paste_params_button exist.
• Reviewer to confirm no regression on stock A1111 / older Forge
  (the alias was a thin re-export; this change just skips the
  indirection).

[zanllp]

Thanks for the PR! This issue has already been fixed in #947, so I'll leave this one as-is for now. Really appreciate your contribution though!