Add frontmatter, markdown, path, xml, rss, and web packages

Sync local packages into the registry repo and update index.json
and README.md to include all 9 packages.

packages/rss/lib.lux

@@ -0,0 +1,101 @@
+// rss - RSS 2.0 feed generator for Lux
+//
+// Generates valid RSS 2.0 XML feeds from structured data.
+
+import xml
+
+// An RSS feed item
+type Item =
+    | Item(String, String, String, String, String)
+    // Item(title, link, description, pubDate, guid)
+
+// An RSS channel/feed
+type Feed =
+    | Feed(String, String, String, String, List<Item>)
+    // Feed(title, link, description, language, items)
+
+// Create a feed item
+pub fn item(title: String, link: String, description: String, pubDate: String): Item =
+    Item(title, link, description, pubDate, link)
+
+// Create a feed item with custom GUID
+pub fn itemWithGuid(title: String, link: String, description: String, pubDate: String, guid: String): Item =
+    Item(title, link, description, pubDate, guid)
+
+// Create an RSS feed
+pub fn feed(title: String, link: String, description: String, items: List<Item>): Feed =
+    Feed(title, link, description, "en", items)
+
+// Create an RSS feed with language
+pub fn feedWithLang(title: String, link: String, description: String, language: String, items: List<Item>): Feed =
+    Feed(title, link, description, language, items)
+
+// Access item fields
+pub fn itemTitle(i: Item): String = match i { Item(t, _, _, _, _) => t, }
+pub fn itemLink(i: Item): String = match i { Item(_, l, _, _, _) => l, }
+pub fn itemDescription(i: Item): String = match i { Item(_, _, d, _, _) => d, }
+pub fn itemPubDate(i: Item): String = match i { Item(_, _, _, p, _) => p, }
+pub fn itemGuid(i: Item): String = match i { Item(_, _, _, _, g) => g, }
+
+// Convert ISO date (2025-01-29) to RFC 822 format (29 Jan 2025 00:00:00 GMT)
+pub fn isoToRfc822(isoDate: String): String =
+    if String.length(isoDate) < 10 then isoDate
+    else {
+        let year = String.substring(isoDate, 0, 4)
+        let month = String.substring(isoDate, 5, 7)
+        let day = String.substring(isoDate, 8, 10)
+        let monthName = if month == "01" then "Jan"
+            else if month == "02" then "Feb"
+            else if month == "03" then "Mar"
+            else if month == "04" then "Apr"
+            else if month == "05" then "May"
+            else if month == "06" then "Jun"
+            else if month == "07" then "Jul"
+            else if month == "08" then "Aug"
+            else if month == "09" then "Sep"
+            else if month == "10" then "Oct"
+            else if month == "11" then "Nov"
+            else "Dec"
+        day + " " + monthName + " " + year + " 00:00:00 GMT"
+    }
+
+// Render a single item to XML string
+fn renderItemXml(i: Item): String =
+    match i {
+    Item(title, link, desc, pubDate, guid) =>
+        xml.render(xml.el("item", [
+            xml.textEl("title", title),
+            xml.textEl("link", link),
+            xml.textEl("description", desc),
+            xml.textEl("pubDate", isoToRfc822(pubDate)),
+            xml.textElAttr("guid", [xml.attr("isPermaLink", "true")], guid)
+        ])),
+}
+
+// Render items to concatenated XML string
+fn renderItemsXml(items: List<Item>): String =
+    match List.head(items) {
+    None => "",
+    Some(i) => renderItemXml(i) + match List.tail(items) {
+        Some(rest) => renderItemsXml(rest),
+        None => "",
+    },
+}
+
+// Render an RSS feed to XML string
+pub fn render(f: Feed): String =
+    match f {
+    Feed(title, link, desc, lang, items) => {
+        let itemsXml = renderItemsXml(items)
+        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
+        "<rss version=\"2.0\" xmlns:atom=\"http://www.w3.org/2005/Atom\">" +
+        "<channel>" +
+        "<title>" + xml.escape(title) + "</title>" +
+        "<link>" + xml.escape(link) + "</link>" +
+        "<description>" + xml.escape(desc) + "</description>" +
+        "<language>" + lang + "</language>" +
+        "<generator>Lux RSS Package</generator>" +
+        itemsXml +
+        "</channel></rss>"
+    },
+}