feat(lexer): add type system keywords

Added four keywords for new type system:
- concept: Base type definition
- sub_concept: Enum/record sub-type definition
- concept_comparison: Compile-time enum mapping
- any: Universal type for dynamic contexts

Also added:
- CLAUDE.md with project instructions and commit guidelines
- Test coverage for new keywords
- Crate-level deny directives for unused variables and dead code

Fixed pre-existing clippy issues to pass pre-commit hooks.

src/lsp/completion.rs

@@ -290,17 +290,12 @@ fn get_contextual_field_completions(doc: &Document, offset: usize) -> Option<Vec
             | Declaration::Template(template) => {
                 // Check if cursor is inside this template block
                 if offset >= template.span.start && offset <= template.span.end {
-                    let mut items = Vec::new();
-
-                    // Add special keywords for templates
-                    items.push(simple_item(
+                    // Templates can suggest common field patterns
+                    return Some(vec![simple_item(
                         "include",
                         "Include a template",
                         "include ${1:TemplateName}",
-                    ));
-
-                    // Templates can suggest common field patterns
-                    return Some(items);
+                    )]);
                 }
             },
             | _ => {},
@@ -494,16 +489,18 @@ fn determine_context(text: &str, offset: usize) -> CompletionContext {
 
     for (_offset, token, _end) in &tokens {
         match token {
-            | Token::LBrace => nesting_level += 1,
+            | Token::LBrace => {
+                nesting_level += 1;
+                if seen_colon_without_brace {
+                    // Opening brace after colon - we've entered the block
+                    seen_colon_without_brace = false;
+                }
+            },
             | Token::RBrace => nesting_level = nesting_level.saturating_sub(1),
             | Token::Colon => {
                 // Mark that we've seen a colon
                 seen_colon_without_brace = true;
             },
-            | Token::LBrace if seen_colon_without_brace => {
-                // Opening brace after colon - we've entered the block
-                seen_colon_without_brace = false;
-            },
             | Token::Ident(keyword)
                 if matches!(
                     keyword.as_str(),