refactor(face-restore): drop GFPGAN, ship PhotoMaker-V2 as the sole restore (non-commercial)

Visual review of the GFPGAN-on-cleaned output (9-face grid, 1448x1086) showed it
only polished the already-drifted face without restoring identity — useless for the
"restore who is in the photo" intent. Dropping it.

The shipped restore path is now PhotoMaker-V2, which delivers true identity-from-
embedding face regeneration via a CLIP+ArcFace dual encoder. The ArcFace branch
pulls InsightFace antelopev2/buffalo_l model packs at runtime, which InsightFace
releases under a research-only license, so the whole extra is **NON-COMMERCIAL**.
raiw.cc and any monetized deployment must NOT install the `photomaker` extra.
This is called out at every entry point: CLI flag help, module docstring,
pyproject extra block, CLAUDE.md extras bullet, README install snippet.

Changes:
- Deleted `src/remove_ai_watermarks/face_restore.py` and its tests.
- Deleted the `restore` extra (gfpgan/facexlib/basicsr + scipy<1.18 / numba<0.60
  pins) and the basicsr setuptools<69 build pin from pyproject.toml.
- Restored `src/remove_ai_watermarks/photomaker_restore.py` (V2 this time:
  `TencentARC/PhotoMaker-V2`, `photomaker-v2.bin`, no `pm_version='v1'` override).
- Restored the `photomaker` extra in pyproject with all the upstream-compat
  pins (einops, peft, onnxruntime, insightface) and the `allow-direct-references`
  hatch metadata block.
- `InvisibleEngine` swapped `_restore_faces` -> `_restore_faces_photomaker`;
  `--restore-faces-method` removed (only one method, no choice).
- CLI flag help, CLAUDE.md, README, docs/synthid.md, and
  docs/controlnet-removal-pipeline-research.md all updated.
- docs/synthid-robust-identity-research.md status notice rewritten to list both
  abandoned commercial-safe attempts (V1 + GFPGAN-on-cleaned) and the
  non-commercial trade-off we accepted.

ruff + strict pyright(src/) clean; 578 tests pass (the 9 GFPGAN tests are gone,
the 11 PhotoMaker tests stay green).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/synthid.md

@@ -570,7 +570,7 @@ table.
 schedule to `resolve_strength`, do not reuse the default ladder; (2) the
 `--restore-faces` pass is now SynthID-safe by construction (the GFPGAN-on-original
 path that re-added SynthID was removed 2026-06-04; the shipped restore is
-GFPGAN-on-cleaned, see `face_restore.py`); (3)
+PhotoMaker-V2, NON-COMMERCIAL, see `photomaker_restore.py`); (3)
 removal near threshold is seed-non-deterministic -> FIX the prod seed (kills the
 coin-flip; ship a deterministic certified config).