Turn the image library into a file library, with a per-blog upload limit

Bloggers want to attach PDFs, archives, audio and other files to posts,
not only images. The Images tab becomes Files: any type is accepted,
listed by kind with search, paging, rename and multi-file upload, and the
editor's paste/drop/"Insert file" takes anything (images are shown,
everything else becomes a link). The default limit goes from 5 to 10 MB
and the superadmin can override it per blog from /admin/.

Files stay in Postgres so one pg_dump is still the whole blog. The bytea
column is STORAGE EXTERNAL and /media streams it in substring() slices,
so serving never holds a whole file in memory whatever limit a blog gets.

Serving any type on the root domain, which carries the session cookie,
needs a policy: uploads are typed by sniffing (the extension may only
refine a generic sniff to an allowlisted type) and only images, PDF,
plain text, audio and video render inline; HTML, SVG, XML, scripts,
archives and binaries always go out as application/octet-stream with
Content-Disposition: attachment.

The body cap moves out of requireAuth into guardPOST, which runs after
withBlog has resolved the blog and so knows its limit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Sd8UPWrvyYCLj97JexNw3A

1 files changed, 3 insertions, 3 deletions

diff --git a/internal/config/config.go b/internal/config/config.go
index 7a3a79c..a239aa2 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -17,8 +17,8 @@ type Config struct {
 	// Bootstrap superadmin created on first start if no superadmin exists.
 	SuperadminUsername string
 	SuperadminPassword string
-	MaxUploadBytes     int64
-	Dev                bool // reload templates/static from disk
+	MaxUploadBytes     int64 // default per-file limit; the superadmin can override it per blog
+	Dev                bool  // reload templates/static from disk
 }
 
 func Load() (*Config, error) {
@@ -32,7 +32,7 @@ func Load() (*Config, error) {
 		SuperadminPassword: env("SUPERADMIN_PASSWORD", ""),
 		Dev:                envBool("DEV", false),
 	}
-	mb, err := strconv.Atoi(env("MAX_UPLOAD_MB", "5"))
+	mb, err := strconv.Atoi(env("MAX_UPLOAD_MB", "10"))
 	if err != nil || mb <= 0 {
 		return nil, fmt.Errorf("MAX_UPLOAD_MB must be a positive integer")
 	}