Render invoice-editor <img> elements on their own line

<img> is a nominally inline HTML element, but TinyMCE content places images
between paragraphs of text; without a forced line break before/after, an
image could render packed against adjacent text in the PDF. Insert a line
break ahead of the image (unless one is already there) and always after it.
Also fixes the img handler's early-return path to still apply the inline
size cap (MaxInlineImageWidth/Height) when only one of width/height was
resized, matching the aspect-ratio-locked branch.

Fuchs/wwwroot/web/tools.js: cosmetic gulp rebuild diff (leading blank line),
no behavior change.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Fuchs/code/MigraDocExtensions.cs

@@ -122,7 +122,9 @@ namespace MigraDoc.Extensions.Html
             // else (including any remote URL the caller didn't fetch/vet) is silently dropped, same
             // as every other unsupported element. Size mirrors what the editor shows (the width/height
             // TinyMCE writes onto the <img> from its resize handles), capped so a stray huge size from
-            // hand-edited HTML can't blow out the invoice table layout.
+            // hand-edited HTML can't blow out the invoice table layout. Always rendered alone on its
+            // own line — surrounded by line breaks rather than left inline with adjacent text — even
+            // though <img> is nominally an inline HTML element.
             _handlers["img"] = (n, p) =>
             {
                 string src = n.GetAttributeValue("src", "");
@@ -130,6 +132,11 @@ namespace MigraDoc.Extensions.Html
                     return p;
                 var para = GetPara(p);
                 if (para == null) return p;
+
+                var existing = para.Elements.Cast<DocumentObject>().ToList();
+                bool lastIsLineBreak = existing.Count > 0 && existing[^1] is Character { SymbolName: SymbolName.LineBreak };
+                if (existing.Count > 0 && !lastIsLineBreak) para.AddLineBreak();
+
                 var img = para.AddImage(source);
                 img.LockAspectRatio = true;
 
@@ -152,13 +159,17 @@ namespace MigraDoc.Extensions.Html
                         img.Width  = Unit.FromCentimeter(img.Width.Centimeter  * scale);
                         img.Height = Unit.FromCentimeter(img.Height.Centimeter * scale);
                     }
-                    return para;
                 }
+                else
+                {
                     if (wPx is > 0) img.Width  = PxToUnit(wPx.Value);
                     else if (hPx is > 0) img.Height = PxToUnit(hPx.Value);
 
                     if (img.Width > MaxInlineImageWidth)   { img.LockAspectRatio = true; img.Width  = MaxInlineImageWidth; }
                     if (img.Height > MaxInlineImageHeight) { img.LockAspectRatio = true; img.Height = MaxInlineImageHeight; }
+                }
+
+                para.AddLineBreak();
                 return para;
             };