fix: replace Python 3.10+ union type syntax with typing.Optional for Pydantic v2 compat

from __future__ import annotations breaks Pydantic BaseModel runtime type
evaluation. Replaced str | None → Optional[str], list[str] → List[str] etc.
in control_generator.py, anchor_finder.py, control_generator_routes.py.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-compliance/compliance/services/anchor_finder.py

@@ -8,10 +8,9 @@ Two-stage search:
 Only open-source references (Rule 1+2) are accepted as anchors.
 """
 
-from __future__ import annotations
-
 import logging
 from dataclasses import dataclass
+from typing import List, Optional
 
 import httpx
 
@@ -40,7 +39,7 @@ class OpenAnchor:
 class AnchorFinder:
     """Finds open-source references to anchor generated controls."""
 
-    def __init__(self, rag_client: ComplianceRAGClient | None = None):
+    def __init__(self, rag_client: Optional[ComplianceRAGClient] = None):
         self.rag = rag_client or get_rag_client()
 
     async def find_anchors(
@@ -48,7 +47,7 @@ class AnchorFinder:
         control: GeneratedControl,
         skip_web: bool = False,
         min_anchors: int = 2,
-    ) -> list[OpenAnchor]:
+    ) -> List[OpenAnchor]:
         """Find open-source anchors for a control."""
         # Stage A: RAG-internal search
         anchors = await self._search_rag_for_open_anchors(control)
@@ -64,7 +63,7 @@ class AnchorFinder:
 
         return anchors
 
-    async def _search_rag_for_open_anchors(self, control: GeneratedControl) -> list[OpenAnchor]:
+    async def _search_rag_for_open_anchors(self, control: GeneratedControl) -> List[OpenAnchor]:
         """Search RAG for chunks from open sources matching the control topic."""
         # Build search query from control title + first 3 tags
         tags_str = " ".join(control.tags[:3]) if control.tags else ""
@@ -76,7 +75,7 @@ class AnchorFinder:
             top_k=15,
         )
 
-        anchors: list[OpenAnchor] = []
+        anchors: List[OpenAnchor] = []
         seen: set[str] = set()
 
         for r in results:
@@ -109,7 +108,7 @@ class AnchorFinder:
 
         return anchors
 
-    async def _search_web(self, control: GeneratedControl) -> list[OpenAnchor]:
+    async def _search_web(self, control: GeneratedControl) -> List[OpenAnchor]:
         """Search DuckDuckGo Instant Answer API for open references."""
         keywords = f"{control.title} security control OWASP NIST"
         try:
@@ -127,7 +126,7 @@ class AnchorFinder:
                     return []
 
                 data = resp.json()
-                anchors: list[OpenAnchor] = []
+                anchors: List[OpenAnchor] = []
 
                 # Parse RelatedTopics
                 for topic in data.get("RelatedTopics", [])[:10]:
@@ -156,7 +155,7 @@ class AnchorFinder:
             return []
 
     @staticmethod
-    def _identify_framework_from_url(url: str) -> str | None:
+    def _identify_framework_from_url(url: str) -> Optional[str]:
         """Identify if a URL belongs to a known open-source framework."""
         url_lower = url.lower()
         if "owasp.org" in url_lower: