refac: removed 7 direct and 12 indirect go modules for custom code instead

docs/image-variants.md

@@ -36,7 +36,7 @@ setting does, so a client holding an old value gets a fresh 200. `Cache-Control`
 Every generated file is a blob in `image.Storage` (local directory or S3) plus a row in
 `image_variant_files` (variant, source stored name, cached stored name, content type, size, settings
 fingerprint). The pair (variant, source) is unique. Concurrent first requests share one generation
-(`singleflight` keyed by variant, settings and source); different variants or different images are
+(a single-flight group keyed by variant, settings and source); different variants or different images are
 generated in parallel.
 
 Only a stored name that has an image record can be a variant source, so generated files and orphan blobs