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.

Language fixes discovered during development:
- Add \{ and \} escape sequences in string literals (lexer)
- Register String.indexOf and String.lastIndexOf in type checker
- Fix formatter to preserve brace escapes in string literals
- Improve LSP hover to show documentation for let bindings and functions

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

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

src/symbol_table.rs

@@ -228,13 +228,14 @@ impl SymbolTable {
             Declaration::Let(let_decl) => {
                 let is_public = matches!(let_decl.visibility, Visibility::Public);
                 let type_sig = let_decl.typ.as_ref().map(|t| self.type_expr_to_string(t));
-                let symbol = self.new_symbol(
+                let mut symbol = self.new_symbol(
                     let_decl.name.name.clone(),
                     SymbolKind::Variable,
                     let_decl.span,
                     type_sig,
                     is_public,
                 );
+                symbol.documentation = let_decl.doc.clone();
                 let id = self.add_symbol(scope_idx, symbol);
                 self.add_reference(id, let_decl.name.span, true, true);
 
@@ -279,13 +280,14 @@ impl SymbolTable {
         };
         let type_sig = format!("fn {}({}): {}{}{}", f.name.name, param_types.join(", "), return_type, properties, effects);
 
-        let symbol = self.new_symbol(
+        let mut symbol = self.new_symbol(
             f.name.name.clone(),
             SymbolKind::Function,
             f.name.span,
             Some(type_sig),
             is_public,
         );
+        symbol.documentation = f.doc.clone();
         let fn_id = self.add_symbol(scope_idx, symbol);
         self.add_reference(fn_id, f.name.span, true, false);
 
@@ -326,13 +328,14 @@ impl SymbolTable {
         let is_public = matches!(t.visibility, Visibility::Public);
         let type_sig = format!("type {}", t.name.name);
 
-        let symbol = self.new_symbol(
+        let mut symbol = self.new_symbol(
             t.name.name.clone(),
             SymbolKind::Type,
             t.name.span,
             Some(type_sig),
             is_public,
         );
+        symbol.documentation = t.doc.clone();
         let type_id = self.add_symbol(scope_idx, symbol);
         self.add_reference(type_id, t.name.span, true, false);
 
@@ -372,13 +375,14 @@ impl SymbolTable {
         let is_public = true; // Effects are typically public
         let type_sig = format!("effect {}", e.name.name);
 
-        let symbol = self.new_symbol(
+        let mut symbol = self.new_symbol(
             e.name.name.clone(),
             SymbolKind::Effect,
             e.name.span,
             Some(type_sig),
             is_public,
         );
+        symbol.documentation = e.doc.clone();
         let effect_id = self.add_symbol(scope_idx, symbol);
 
         // Add operations
@@ -409,13 +413,14 @@ impl SymbolTable {
         let is_public = matches!(t.visibility, Visibility::Public);
         let type_sig = format!("trait {}", t.name.name);
 
-        let symbol = self.new_symbol(
+        let mut symbol = self.new_symbol(
             t.name.name.clone(),
             SymbolKind::Type, // Traits are like types
             t.name.span,
             Some(type_sig),
             is_public,
         );
+        symbol.documentation = t.doc.clone();
         self.add_symbol(scope_idx, symbol);
     }