feat(backend): add API routes

backend/src/api/routes/patterns.py

@@ -0,0 +1,81 @@
+from collections.abc import AsyncGenerator
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from src.db.database import get_db
+from src.schemas import (
+    PatternDetailResponse,
+    PatternListResponse,
+    PatternResponse,
+    PatternTutorialResponse,
+)
+from src.services import PatternService
+
+router = APIRouter()
+
+
+async def get_pattern_service(
+    db: Annotated[AsyncSession, Depends(get_db)],
+) -> AsyncGenerator[PatternService, None]:
+    """Dependency for PatternService."""
+    yield PatternService(db)
+
+
+@router.get("", response_model=PatternListResponse)
+async def list_patterns(
+    service: Annotated[PatternService, Depends(get_pattern_service)],
+) -> PatternListResponse:
+    """List all patterns with question counts."""
+    patterns_with_counts = await service.get_patterns()
+
+    items = [
+        PatternResponse(
+            id=pattern.id,
+            name=pattern.name,
+            slug=pattern.slug,
+            description=pattern.description,
+            when_to_use=pattern.when_to_use,
+            question_count=count,
+        )
+        for pattern, count in patterns_with_counts
+    ]
+
+    return PatternListResponse(items=items)
+
+
+@router.get("/{slug}", response_model=PatternDetailResponse)
+async def get_pattern(
+    slug: str,
+    service: Annotated[PatternService, Depends(get_pattern_service)],
+) -> PatternDetailResponse:
+    """Get a single pattern by slug with details."""
+    result = await service.get_pattern_by_slug(slug)
+
+    if not result:
+        raise HTTPException(status_code=404, detail="Pattern not found")
+
+    pattern, count = result
+    return PatternDetailResponse(
+        id=pattern.id,
+        name=pattern.name,
+        slug=pattern.slug,
+        description=pattern.description,
+        when_to_use=pattern.when_to_use,
+        question_count=count,
+    )
+
+
+@router.get("/{slug}/tutorial", response_model=PatternTutorialResponse)
+async def get_pattern_tutorial(
+    slug: str,
+    service: Annotated[PatternService, Depends(get_pattern_service)],
+) -> PatternTutorialResponse:
+    """Get full pattern tutorial with educational content and learning progression."""
+    tutorial = await service.get_pattern_tutorial(slug)
+
+    if not tutorial:
+        raise HTTPException(status_code=404, detail="Pattern not found")
+
+    return tutorial