fix: Real-ESRGAN install + Cookbook deps-panel crash on the Python 3.14 image (#4694)

* fix(docker): make Real-ESRGAN installable on the Python 3.14 image

realesrgan's deps basicsr/gfpgan/facexlib (unmaintained since 2022) read
their version in setup.py via `exec(...); locals()['__version__']`, which
raises KeyError on Python 3.13+ — PEP 667 made locals() in a function an
independent snapshot that exec() can no longer mutate. That fails the
Cookbook "install realesrgan" sdist build on the python:3.14 base.

Add a `realesrgan-wheels` builder stage that fetches the pinned sdists,
patches get_version() to exec into an explicit namespace dict, and builds
wheels; the final stage installs them --no-deps so a later
`pip install realesrgan` resolves from wheels instead of rebuilding the
broken sdists. torch stays a runtime pull to keep the base image lean.

Also add the runtime libs opencv-python (cv2) needs — libgl1,
libglib2.0-0t64, libxcb1 — which the slim base omits; without them the
install succeeds but `import cv2` dies with
`libxcb.so.1: cannot open shared object file`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(cookbook): don't let a package's sys.exit() on import hang the deps panel

The local optional-dependency probe imports each package in-process and
catches ImportError / Exception. But a package can call sys.exit() at
import time — e.g. rembg does `sys.exit(1)` when no onnxruntime backend
loads. SystemExit is a BaseException, not Exception, so it escaped the
probe, propagated out of the list_packages endpoint, and hung the whole
Dependencies panel / worker (the UI loads forever).

Catch (Exception, SystemExit) so one broken optional package is reported
as not-usable instead of taking down the panel.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

routes/shell_routes.py

@@ -1377,11 +1377,16 @@ def setup_shell_routes() -> APIRouter:
                     pkg["installed"] = False
                 except importlib_metadata.PackageNotFoundError:
                     pkg["installed"] = False
-                except Exception:
+                except (Exception, SystemExit):
                     # Installed but crashes on import — e.g. a CUDA build of
                     # llama-cpp-python raising FileNotFoundError when the CUDA
-                    # toolkit dir is absent. One broken optional package must not
-                    # 500 the entire packages panel; report it as not usable.
+                    # toolkit dir is absent, or rembg calling sys.exit(1) when no
+                    # onnxruntime backend can be loaded. SystemExit is a
+                    # BaseException, not Exception, so without catching it here a
+                    # single sys.exit-on-import package escapes and takes down the
+                    # whole packages panel / worker (the panel hangs forever). One
+                    # broken optional package must not 500 — or hang — the entire
+                    # panel; report it as not usable.
                     pkg["installed"] = False
 
             # llama_cpp partial-state probe: when the package is installed