Rename content_hash/output_hash to cid throughout

Refactor to use IPFS CID as the primary content identifier:
- Update database schema: content_hash -> cid, output_hash -> output_cid
- Update all services, routers, and tasks to use cid terminology
- Update HTML templates to display CID instead of hash
- Update cache_manager parameter names
- Update README documentation

This completes the transition to CID-only content addressing.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/services/recipe_service.py

@@ -27,7 +27,7 @@ class RecipeService:
     async def get_recipe(self, recipe_id: str) -> Optional[Dict[str, Any]]:
         """Get a recipe by ID (content hash)."""
         # Get from cache (content-addressed storage)
-        path = self.cache.get_by_content_hash(recipe_id)
+        path = self.cache.get_by_cid(recipe_id)
         if not path or not path.exists():
             return None
 
@@ -70,8 +70,8 @@ class RecipeService:
         if hasattr(self.cache, 'list_by_type'):
             items = self.cache.list_by_type('recipe')
             logger.info(f"Found {len(items)} recipes in cache")
-            for content_hash in items:
-                recipe = await self.get_recipe(content_hash)
+            for cid in items:
+                recipe = await self.get_recipe(cid)
                 if recipe and not recipe.get("error"):
                     owner = recipe.get("owner")
                     # Filter by actor - L1 is per-user
@@ -114,7 +114,7 @@ class RecipeService:
 
             # Store in cache (content-addressed, auto-pins to IPFS)
             cached, ipfs_cid = self.cache.put(tmp_path, node_type="recipe", move=True)
-            recipe_id = cached.content_hash
+            recipe_id = cached.cid
 
             return recipe_id, None
 
@@ -140,12 +140,12 @@ class RecipeService:
 
         # Delete from cache
         try:
-            if hasattr(self.cache, 'delete_by_content_hash'):
-                success, msg = self.cache.delete_by_content_hash(recipe_id)
+            if hasattr(self.cache, 'delete_by_cid'):
+                success, msg = self.cache.delete_by_cid(recipe_id)
                 if not success:
                     return False, msg
             else:
-                path = self.cache.get_by_content_hash(recipe_id)
+                path = self.cache.get_by_cid(recipe_id)
                 if path and path.exists():
                     path.unlink()