Remove content fallback, fix README tool docs

- Drop the content alias from store_knowledge handler
- Fix error message to say 'note' only
- Correct README store_knowledge params to match actual API
- Fix EMBEDDING_BASE_URL default (no /v1 suffix)

main.go

@@ -172,11 +172,7 @@ func handleStoreKnowledge(sqlite *sqliteStore, qdrant *qdrantStore, logger *zap.
 
 		note, ok := args["note"].(string)
 		if !ok || note == "" {
-			if content, ok := args["content"].(string); ok && content != "" {
-				note = content
-			} else {
-				return mcp.NewToolResultError("note (or content) is required and must be a non-empty string"), nil
-			}
+			return mcp.NewToolResultError("note is required and must be a non-empty string"), nil
 		}
 
 		repos := parseStringSlice(args["repos"])