Split pure-config into invisible-core; keep back-compat shims

The seed->fingerprint->prefs logic, binary download, and proxy/geo config
now live in a standalone invisible-core package (zero Playwright), so a
profile manager can reuse it without pulling Playwright in. The wrapper
depends on invisible-core and replaces the moved modules with full-alias
shims: existing imports (public API, submodules, private names) and
isinstance checks keep working unchanged. tests/test_backcompat.py locks
that contract (6 guards). Bumps to 0.3.0.

tests/test_backcompat.py

@@ -0,0 +1,84 @@
+"""Backward-compatibility guard for the invisible_core / invisible_playwright split.
+
+After extracting the pure config into ``invisible_core`` and turning the moved
+modules into aliasing shims, EVERY import path that external users (and our own
+outreach PRs) rely on must keep working — same objects, same behavior. This test
+is the contract: if it breaks, we broke someone's install.
+"""
+import importlib
+
+import pytest
+
+
+@pytest.mark.unit
+def test_top_level_public_api_imports():
+    import invisible_playwright as ip
+    for name in [
+        "InvisiblePlaywright", "ensure_binary", "ensure_geoip_mmdb",
+        "get_default_stealth_prefs", "get_default_args",
+        "resolve_session_timezone", "GeoTimezoneError",
+        "BINARY_VERSION", "FIREFOX_UPSTREAM_VERSION", "__version__",
+    ]:
+        assert hasattr(ip, name), f"invisible_playwright.{name} missing"
+
+
+@pytest.mark.unit
+def test_submodule_imports_external_users_rely_on():
+    # These are the exact import shapes used in the wild + in our Skyvern/onyx/etc PRs.
+    from invisible_playwright._fpforge import generate_profile, Profile  # noqa: F401
+    from invisible_playwright._webgl_personas import forced_gpu_class      # noqa: F401
+    from invisible_playwright.prefs import translate_profile_to_prefs      # noqa: F401
+    from invisible_playwright.download import ensure_binary                # noqa: F401
+    from invisible_playwright.constants import BINARY_VERSION              # noqa: F401
+    from invisible_playwright.config import get_default_stealth_prefs      # noqa: F401
+
+
+@pytest.mark.unit
+def test_deep_submodule_and_private_names_still_import():
+    from invisible_playwright._fpforge.profile import Profile              # noqa: F401
+    from invisible_playwright._fpforge import _sampler                     # noqa: F401
+    from invisible_playwright.prefs import _BASELINE                       # noqa: F401
+    assert isinstance(_BASELINE, dict)
+
+
+@pytest.mark.unit
+def test_class_identity_is_shared_with_core():
+    # isinstance must hold: the object returned by generate_profile must be an
+    # instance of BOTH the invisible_playwright-path Profile and the core Profile
+    # (they must be the SAME class object, not duplicates).
+    from invisible_playwright._fpforge import generate_profile
+    from invisible_playwright._fpforge import Profile as PW_Profile
+    from invisible_playwright._fpforge.profile import Profile as PW_Profile2
+    import invisible_core
+    from invisible_core import Profile as Core_Profile
+
+    p = generate_profile(seed=42)
+    assert isinstance(p, PW_Profile)
+    assert isinstance(p, PW_Profile2)
+    assert isinstance(p, Core_Profile)
+    assert PW_Profile is Core_Profile
+    assert PW_Profile2 is Core_Profile
+
+
+@pytest.mark.unit
+def test_shim_output_matches_core_output():
+    from invisible_playwright._fpforge import generate_profile as gp_pw
+    from invisible_playwright._webgl_personas import forced_gpu_class as fgc_pw
+    from invisible_playwright.prefs import translate_profile_to_prefs as tp_pw
+    import invisible_core as ic
+
+    a = tp_pw(gp_pw(42, fixed_gpu_class=fgc_pw(42)))
+    b = ic.translate_profile_to_prefs(ic.generate_profile(42, fixed_gpu_class=ic.forced_gpu_class(42)))
+    assert a == b
+
+
+@pytest.mark.unit
+def test_core_imports_without_playwright(monkeypatch):
+    # invisible_core must be importable even if playwright is absent. We simulate
+    # by asserting the core modules never pulled playwright into sys.modules as a
+    # side effect of their own import (the wrapper may have, but core must not need it).
+    import sys
+    import invisible_core  # noqa: F401
+    # invisible_core itself must not hard-depend on playwright at import time.
+    core_file = importlib.import_module("invisible_core").__file__
+    assert "invisible_core" in core_file