feat(sub): add raw subscription download actions (#6017)

* feat(sub): add raw subscription downloads

* fix(sub): address review feedback

* feat(sub): add download buttons to client subscriptions

* fix(sub): fetch subscription before download

---------

Co-authored-by: w3struk <w3struk@gmail.com>

internal/sub/dist.go

@@ -1,16 +1,16 @@
 package sub
 
-import "embed"
+import "io/fs"
 
 // distFS holds the Vite-built frontend filesystem, injected from main at
 // startup. The `web` package owns the //go:embed directive (because dist/
 // is at internal/web/dist/), and hands the FS over via SetDistFS so the sub package
 // doesn't import web — that would create an import cycle once any
 // internal/web/controller handler reuses sub's link-building service.
-var distFS embed.FS
+var distFS fs.FS
 
 // SetDistFS installs the embedded frontend filesystem the sub server uses
 // for its info page assets. Must be called before NewServer().Start().
-func SetDistFS(fs embed.FS) {
-	distFS = fs
+func SetDistFS(frontendFS fs.FS) {
+	distFS = frontendFS
 }