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/frontmatter/test_integration.lux

@@ -0,0 +1,87 @@
+import lib
+
+// Integration tests: realistic document processing workflows
+
+// Parse a complete blog post and extract all metadata
+fn test_complete_blog_post(): Unit with {Test} = {
+    let content = "---\ntitle: My First Post\ndate: 2025-01-29\ndescription: A great introduction\ntags: web lux programming\nauthor: Brandon\n---\nThis is the body of my post.\n\nIt has multiple paragraphs."
+    let doc = lib.parse(content)
+    Test.assertEqualMsg(true, lib.hasFrontmatter(doc), "has frontmatter")
+    Test.assertEqualMsg("My First Post", lib.title(doc), "title")
+    Test.assertEqualMsg("2025-01-29", lib.date(doc), "date")
+    Test.assertEqualMsg("A great introduction", lib.description(doc), "description")
+    Test.assertEqualMsg(3, List.length(lib.tags(doc)), "tag count")
+    Test.assertEqualMsg("Brandon", lib.getOrDefault(doc, "author", ""), "author field")
+    Test.assert(String.startsWith(lib.body(doc), "This is the body"), "body starts correctly")
+}
+
+// Parse multiple documents and compare metadata
+fn test_parse_multiple_documents(): Unit with {Test} = {
+    let doc1 = lib.parse("---\ntitle: Post A\ndate: 2025-01-01\n---\nBody A")
+    let doc2 = lib.parse("---\ntitle: Post B\ndate: 2025-02-01\n---\nBody B")
+    let doc3 = lib.parse("---\ntitle: Post C\ndate: 2025-03-01\n---\nBody C")
+    Test.assertEqualMsg("Post A", lib.title(doc1), "doc1 title")
+    Test.assertEqualMsg("Post B", lib.title(doc2), "doc2 title")
+    Test.assertEqualMsg("Post C", lib.title(doc3), "doc3 title")
+    Test.assertEqualMsg(true, lib.hasFrontmatter(doc1), "doc1 has frontmatter")
+    Test.assertEqualMsg(true, lib.hasFrontmatter(doc2), "doc2 has frontmatter")
+}
+
+// Simulate a static site generator reading a page
+fn test_ssg_page_workflow(): Unit with {Test} = {
+    let page = "---\ntitle: About Me\ndescription: Learn about the author\nlayout: page\n---\n# About\n\nI write software."
+    let doc = lib.parse(page)
+    let pageTitle = lib.title(doc)
+    let pageDesc = lib.description(doc)
+    let layout = lib.getOrDefault(doc, "layout", "default")
+    let body = lib.body(doc)
+    Test.assertEqualMsg("About Me", pageTitle, "page title")
+    Test.assertEqualMsg("Learn about the author", pageDesc, "page description")
+    Test.assertEqualMsg("page", layout, "layout field")
+    Test.assert(String.startsWith(body, "# About"), "body starts with heading")
+}
+
+// Extract custom fields beyond the standard ones
+fn test_custom_fields(): Unit with {Test} = {
+    let doc = lib.parse("---\ntitle: Post\nslug: custom-slug\ndraft: true\nweight: 10\n---\nContent")
+    Test.assertEqualMsg("custom-slug", lib.getOrDefault(doc, "slug", ""), "custom slug field")
+    Test.assertEqualMsg("true", lib.getOrDefault(doc, "draft", "false"), "custom draft field")
+    Test.assertEqualMsg("10", lib.getOrDefault(doc, "weight", "0"), "custom weight field")
+}
+
+// Iterate over entries and collect all keys
+fn test_iterate_entries(): Unit with {Test} = {
+    let doc = lib.parse("---\na: 1\nb: 2\nc: 3\n---\nBody")
+    let es = lib.entries(doc)
+    Test.assertEqualMsg(3, List.length(es), "three entries")
+    match List.head(es) {
+        Some(e) => Test.assertEqualMsg("a", lib.entryKey(e), "first entry key"),
+        None => Test.assert(false, "should have entries"),
+    }
+}
+
+// Document with frontmatter but no body
+fn test_frontmatter_only_document(): Unit with {Test} = {
+    let doc = lib.parse("---\ntitle: Metadata Only\ntags: meta\n---")
+    Test.assertEqualMsg("Metadata Only", lib.title(doc), "title from frontmatter-only doc")
+    Test.assertEqualMsg(1, List.length(lib.tags(doc)), "one tag")
+    Test.assertEqualMsg("", lib.body(doc), "empty body")
+}
+
+// Document with all convenience fields
+fn test_all_convenience_fields(): Unit with {Test} = {
+    let doc = lib.parse("---\ntitle: Full Post\ndate: 2025-06-15\ndescription: Complete metadata\ntags: a b c d\n---\nBody text")
+    Test.assertEqualMsg("Full Post", lib.title(doc), "title convenience")
+    Test.assertEqualMsg("2025-06-15", lib.date(doc), "date convenience")
+    Test.assertEqualMsg("Complete metadata", lib.description(doc), "description convenience")
+    Test.assertEqualMsg(4, List.length(lib.tags(doc)), "tags convenience")
+}
+
+// Fallback behavior when fields are missing
+fn test_missing_field_defaults(): Unit with {Test} = {
+    let doc = lib.parse("---\ntitle: Minimal\n---\nBody")
+    Test.assertEqualMsg("Minimal", lib.title(doc), "title present")
+    Test.assertEqualMsg("", lib.date(doc), "date defaults to empty")
+    Test.assertEqualMsg("", lib.description(doc), "description defaults to empty")
+    Test.assertEqualMsg(0, List.length(lib.tags(doc)), "tags defaults to empty")
+}