feat: add blu-site static site generator and fix language issues

Build a complete static site generator in Lux that faithfully clones
blu.cx (elmstatic). Generates 14 post pages, section indexes, tag pages,
and a home page with snippets grid from markdown content.

ISSUES.md documents 15 Lux language limitations found during the project.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

config.lux

@@ -0,0 +1,60 @@
+// Site configuration loaded from config.json
+
+pub type SiteConfig =
+    | SiteConfig(String, String, String, String, String, String, String)
+    //           title   url     author  desc    contentDir outputDir staticDir
+
+pub fn loadConfig(path: String): SiteConfig with {File} = {
+    let raw = File.read(path);
+    let json = match Json.parse(raw) { Ok(j) => j, Err(_) => match Json.parse("\{\}") { Ok(j2) => j2 } };
+    let title = match Json.get(json, "siteTitle") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "Site" },
+        None => "Site"
+    };
+    let url = match Json.get(json, "siteUrl") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "" },
+        None => ""
+    };
+    let author = match Json.get(json, "author") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "" },
+        None => ""
+    };
+    let desc = match Json.get(json, "description") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "" },
+        None => ""
+    };
+    let contentDir = match Json.get(json, "contentDir") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "content" },
+        None => "content"
+    };
+    let outputDir = match Json.get(json, "outputDir") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "_site" },
+        None => "_site"
+    };
+    let staticDir = match Json.get(json, "staticDir") {
+        Some(v) => match Json.asString(v) { Some(s) => s, None => "static" },
+        None => "static"
+    };
+    SiteConfig(title, url, author, desc, contentDir, outputDir, staticDir)
+}
+
+pub fn getTitle(c: SiteConfig): String =
+    match c { SiteConfig(t, _, _, _, _, _, _) => t }
+
+pub fn getUrl(c: SiteConfig): String =
+    match c { SiteConfig(_, u, _, _, _, _, _) => u }
+
+pub fn getAuthor(c: SiteConfig): String =
+    match c { SiteConfig(_, _, a, _, _, _, _) => a }
+
+pub fn getDescription(c: SiteConfig): String =
+    match c { SiteConfig(_, _, _, d, _, _, _) => d }
+
+pub fn getContentDir(c: SiteConfig): String =
+    match c { SiteConfig(_, _, _, _, cd, _, _) => cd }
+
+pub fn getOutputDir(c: SiteConfig): String =
+    match c { SiteConfig(_, _, _, _, _, od, _) => od }
+
+pub fn getStaticDir(c: SiteConfig): String =
+    match c { SiteConfig(_, _, _, _, _, _, sd) => sd }