feat(consent-tester): Phase B — named CMP library + plugin architecture

cmp_extractor.py refactored to thin coordinator (123 LOC, was 223).
Discovers all CMP modules via cmp_library/_registry.py:load_all() at
import time. Restart consent-tester to pick up new modules.

New cmp_library/ folder:
- _registry.py: auto-discovers all modules with MATCHER + reconstruct()
- epaas.py:     BMW Group ePaaS (extracted from cmp_extractor)
- onetrust.py:  cdn.cookielaw.org Groups/Cookies schema
- cookiebot.py: consent.cookiebot.com Categories schema
- usercentrics.py: api.usercentrics.eu services schema
- didomi.py:    sdk.privacy-center.org notice + vendors + purposes
- trustarc.py:  consent.trustarc.com categories + vendors

Each module:
- MATCHER: re.Pattern matching the CMP JSON endpoint URL
- reconstruct(d: dict) -> str: builds German Markdown cookie-policy text

Phase E (self-improving) will write auto_*.py files into the same folder;
_registry already picks those up via pkgutil.iter_modules.

consent-tester/services/cmp_library/_registry.py

@@ -0,0 +1,55 @@
+"""
+CMP Library Registry — discovers and registers all CMP modules.
+
+Each CMP module exports two module-level symbols:
+  - MATCHER: a compiled regex matching the JSON endpoint URL
+  - reconstruct(data: dict) -> str: builds the cookie-policy text from JSON
+
+The registry auto-discovers:
+  1. Hand-written modules: epaas, onetrust, cookiebot, usercentrics,
+     didomi, trustarc
+  2. Auto-promoted modules: any file matching `auto_*.py` in this folder
+     (created by Phase E when an LLM successfully discovers a new pattern)
+
+A consent-tester restart picks up new auto_*.py files automatically.
+"""
+
+from __future__ import annotations
+
+import importlib
+import logging
+import pkgutil
+from pathlib import Path
+from typing import Callable
+
+logger = logging.getLogger(__name__)
+
+# (cmp_name, url_pattern, reconstruct_fn)
+Registry = list[tuple[str, "object", Callable[[dict], str]]]
+
+
+def load_all() -> Registry:
+    """Import every module in this package and collect MATCHER + reconstruct."""
+    import services.cmp_library as pkg  # type: ignore[import-not-found]
+    registry: Registry = []
+
+    pkg_path = Path(pkg.__file__).parent
+    for module_info in pkgutil.iter_modules([str(pkg_path)]):
+        name = module_info.name
+        if name.startswith("_"):
+            continue
+        try:
+            module = importlib.import_module(f"services.cmp_library.{name}")
+            matcher = getattr(module, "MATCHER", None)
+            reconstruct = getattr(module, "reconstruct", None)
+            if matcher is None or not callable(reconstruct):
+                logger.warning(
+                    "CMP module %s missing MATCHER or reconstruct() — skipped", name,
+                )
+                continue
+            registry.append((name, matcher, reconstruct))
+            logger.info("CMP loaded: %s", name)
+        except Exception as e:
+            logger.warning("CMP module %s failed to load: %s", name, e)
+
+    return registry