Support local file URL paths as input to image_style filter

Problem/Motivation

The image_style filter currently only accepts stream wrapper URIs (e.g., public://image.jpg) as input. However, in many contexts, especially when working with SDCs and Canvas, image sources may be provided as local file URLs (e.g., /sites/default/files/image.jpg) rather than stream wrapper URIs.

This limitation makes it difficult to apply image styles to images that come from sources that provide URLs rather than URIs.

Steps to reproduce

Try to apply an image style to a local file URL: {{ '/sites/default/files/image.jpg'|image_style('thumbnail') }}

The filter fails because it doesn't recognize the local file URL format.

Proposed resolution

Change the image_style filter to:

1. Continue to accept stream wrapper URIs as before
2. Also accept local file URLs (e.g., /sites/default/files/image.jpg) by converting them to stream wrapper URIs internally before applying the style

Remaining tasks

User interface changes

API changes

Data model changes