chore: initial commit — existing single-user document scanner codebase

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

backend/ai/base.py

@@ -0,0 +1,32 @@
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+
+
+@dataclass
+class ClassificationResult:
+    topics: list[str] = field(default_factory=list)
+    suggested_new_topics: list[str] = field(default_factory=list)
+    reasoning: str = ""
+
+
+class AIProvider(ABC):
+    @abstractmethod
+    async def classify(
+        self,
+        document_text: str,
+        existing_topics: list[str],
+        system_prompt: str,
+    ) -> ClassificationResult:
+        ...
+
+    @abstractmethod
+    async def suggest_topics(
+        self,
+        document_text: str,
+        system_prompt: str,
+    ) -> list[str]:
+        ...
+
+    @abstractmethod
+    async def health_check(self) -> bool:
+        ...